L.RC.8013
PROCEEDINGS OF THE TOPICAL WORKSHOP ON FORWARD PRODUCTION OF HIGH-MASS FLAVOURS II AT COLLIDER ENERGIES
HELD IN PARIS COLLEGE DE FRANCE
November 28-30 1979
'J3° iCfcr9. QyM*Sl)k\f
/ H Edited by G. Fontaine Laboratoire de Physique Corpusculaire College de Frinct
11. PUce Marcelin Bcrthclot . F75S31 PARIS Cedex 05 PROCEEDINGS OF THE TOPICAL WORKSHOP ON FORWARD PRODUCTION OF HIGH-MASS FLAVOURS AT COLLIDER ENERGIES
HELD IN PARIS COLLEGE DE FRANCE
November 28-30 1979
I S 1 M G C 0 M H 1 T E E :
FONTAINE, M. 'ROISSART, C. GHESQUIERE, J. PRENTKI, G. INTRODUCTION.
Tin.- present volume contains the proceed! n^s of the "Topical Workshop on forward production of hifih-rr.ass flavours at collider energies" held in Paris, ('...lene do France, November JS-10, 1979.
The aim of this workshop was to discuss all the aspects (both experimental and theoretical) of this new domain of Physics recently opened up by the obser vation ni" a penetrating component i n cosmic-ray i nternr i ions and of charmed ::I-S.MIS and baryons in the forward d i reel ion a I l he I.S.I;.. These rel" 1 exi uns weiv further motivated by the preparation of new ;>p colliding facilities of
II'.IH b higher energy and where experiments conii :m soon could prof i t ably cover | this field of interest.
This workshop gathered about 90 participants from 11 countries and gave them the opportunity to exchange information and opinions in a rather informal a trios pi: ere. It is a p ieasure to thank warxl y all of them for thei r cone ri but ion to Lhe success of this meeting, and specially the speakers and those who pré parée1 the workshop in specialised working groups. A particular mention has to be made of Dr. M.K. GALI.I.AK1) and R. PETRONE 10 who have led a fruitful round taille discussion on theoretical aspects, which unfortunately could not be reported i n these proceed i nus. All papers included in the present publicat inn have been reproduced as rhey were prepared by the authors. They are divided into three subjects :
- experimental results - Theoretical aspects - New experiments.
The orjvï:iÎ5ins commî(Coe also wishes to acknowledge the precious help
^i all those who have directly or indirectly contributed to the preparation of cne workshop and of these proceedings :
M. KELLER, (C.E.R.N.); M.S. DETOEUF and M.F. CHICANNE, (I.N2.P3.), C. BREON,
E. BROCHET, G. MASSEl, Y. RUELLE, Y. GIRAUU-HERAUD, T). KRYN, G. ARBOUSSE-BASTIDE, X. LE TAN and J. ORILLON, (Collège de France).
G. FONTAINE 1
A/ KXl'KKIMKNÏAL RKSl'LTS.
Forward Production ol low m.iss flavours at Liu- C.K.R.N. I.S.R.
V. Ci: I ST Kxper iment.i I ri'V i ew of charm hadroproduct ion
y. Mn.i.HK Comments mi 1 prnilucl i nn at the T . S.R. B5 Kq
K. SOSNOU'SKI St rue Lure of I1 rnL on-Pro tun sions with a c harried hadron pr.uîureti.
A. iHAMANT-Br.RCKK Study of the forward production of ti i^h-mnss .systems .-H the I.S.R. 99 ^1
I>. CLINK High energy particLe interactions from 10-1000 TiiV"': Cosmic ray data and Proton- (Awtrff Proton col l.ûJ-c'rs". 109 V . ML'RAKI Cosni c my s and new ace el crator experiments. l2tJ qa
i!/ THKORI-TICAI. ASPECTS.
II. FRITZSCH B particles. i43 q^,
C. PKTKKSON TheDrelica] Predictions for hifih-mass flavour
production in Hadron-Hadron collisions. 155 q 4
P. KKSSLLCR YY versus Drell Yan effect in pp or pp •storage rin^s. 187 4 ST
(7 NEW EXPERIMENTS.
in pp interactions at 540 GeV .n energy 195 W.G. SCOTT Particle identification using dE/dx 209 ^ F. C'.ERADINI fl flavour production in the forward aria of the UA1 experiment. 229 Cff Muon detection and background from normal events for a possible forward muon detector. 257 <3>^> C. GHESQUIERE Study of a muon forward trigger in UAI experiment. 280 | &0 C. KUBBIA Instrumentation developments and potential impact on collider detectors. 297 |0| pp collider at Fermi]ab. 3°9 | Oil LIST OF PARTICIPANTS. ( rOKU'ASD PRODUCTION OF LOW MASS FLAVOURS AT THE CKRN/ISR J.C. Sens 1. INTRODUCTION The purpose of this cent ri but ion is three* fa Id : 1) To .show that in a subset of al l-hadro:iic processes, i.e. the ones in wiii ch a large fraction ol Lhe incident energy is transferred to one single secundary the dominant mechanism may hi- ^lunn exchange. 2) To show that gluon exchange provides a natural explanation for the [acL that baryons (n, :'i, .'. ) rosp. mesons (-, K) are produced with distributions in momentum which decrease slowly, rcsp. rapidly with increasing momentum. 3) To provide a recipe for calculating the distribution in x and p of t\ and \, states which D the SPS pp collider. The data on which the conclusions are based have been obtained witli single and double arm spectrometers placed at very small angle with res pect to the primary beams at the CERN/ISR. Fig. I shows the old, con servatively designed spectrometer dating back to 1970 of exp. R201 ; Fig. 2 shows the stream lined spectrometer operational since 1978 of R607. Typical solid angles are 10 - 10 sr, typical, momentum resolution -£ *= 0.5 - 1 % at 25 - 30 GeV. A typical particle spectrum obtained in 2 minutes ISR time is shown in fig. 3, positives on the ri^ht, negatives on the left. The main features are apparent at once: A rapidly falling specirum of negatives, essentially n , and, at the positive side, an InviLed talk at the workshop on the production of high mass flavours, Paris, November I960. Present address: S1.AC, P.O. Box 4349, Stanford CA 94305 U.S.A. assymetric peak, corresponding to ;lastically and quasi-elastically scattered protons, and at lower momenta a spectrum which is (after subtracting the IT spectrum {=* s pec" rum) from it) flat and consists mostly of protons. Fig. 4, 5 show samples of production spectra obtained with 2. 7T /TT = 2 -* 5 for x = 0.5 - 0.9 3. K+/K~ > 50 for x ? 0.7 U. o(K ) > affr ) for x > 0.7: crossover 5. Perfect scaling (fig. 5) II. GLOBAL COMPARISON pp - MESON/ep -<• eX Assuming a fast v to consist of a valence u quark from the proton, coupled to a slow d quark from the sea we may expect, in first instance, the following relations between the x dependence of the inclusive cross section for ^ , K , " production and the momentum distribution u(x) and d(x): <-.T(/Tr,;t) * T(/C>) xufx.) Vie can then relate the production of fast pions to deep-inelastic lep- ton scattering by noting that for high x, to a good approximation: x ' ? ' '/ Corcp;it i us t ïic (J(.N) ;ind d f .\) from deep-i ne List i c data we obtain l lu1 ivsiil Ls of £ i gs. 6, 7, 8, whuru the 1 ir.es are the computed u(x) and d(>:}, aparC frofl îr.e p-dependent normal iz.it ion constant per particle tvpe. The agreement is good up to x * 0.7( for x • 0.7 there are large tU-vi at ions, as ill us traced also in fig. 9 where various rat j ns are cotn- p.uvd i.i th the computed ration of the quark di st r i butions. V.'c shal 1 sec in-1 ow that these discrepancies can be complete ly removed in a more de~ t.ii l^-c rcodei . III. COL'NTK.'G RULES, OLD AN'D NI-;',; Counting rules are based on :;-ie notion of equiparriLion of energy giver. of f ts tiif proLon by the ether protsr. in the ac:_ of an ini e race ion producing a final state particle. We can classify this process by noting that in an interaction we have an exchange and that we have a number of spectators, who, as spectators do, share in the exci teraent while watching the parade. We have 3 types of exchange: exchange of gluons (g) , valence quarks (qt ) or ^ea quarks (c . ). And there arc two ways of sharing the energy: 1) it gets shared among al1 (valence and sea) quarks standing by while the produced particle leaves the proton (/The Brodsky-Gunion Counting rule") or 2) it gets shared among the valence quarks only ("The valence counting rule"). There is of course the third possib) '. : *-y of sharing among sea quarks only but sea quarks are known (from pp -* -,. ->voerinencs e.g.) to have very small average momenta and steeply falling sea distributions, so chey do not enter into this picture of high x mesonproduction. So with 3 exchanges and 2 ways oî counting the spectators we have 6 possible cases. How do we know whicii is which? The ans'-'er is we don't for sure buL we can try and make the plausible ;is.-un'.pLi'on that the Larger the number of spectators .\' the lower the energy K'f!: for the - will be on average. Thus the rnonenturr: spectrin of titu ~ ::IUSL decrease faster with increasing x, the larger the nuT.bri: ,\". Brod.sky .znd Cimion liave shown from field theory arguments that for N spectators the dependence on x is given by (/-*-)" * = *#-/ & For example tiie inclusive production of ~ mesons of high x and srcalî _ ) ) - n = 2 n=2 n = 1 v v v n = ] n = 0 n » I s s s n=3 n=2 n =2 where n , n is the number of valence and sea spectators and n = n + n • V S ^ V S From eq. (2) we thus have three possible x dependences: [t~x) //-*/ [,-*) (3) depending on the exchange and the manner of counting spectators. S;-ice there are 6 different cases a measurement of the spectral shape alone will not result in a unambiguous solution. The same situation arises in the production of other particles, e.g. for A production we have (/-*)" (/-X)' (S-*)' (y for the possible dependence on x. IV. CUMULATIONS AT 0,1-2 TeV l'art of the remain ins ambi gui ty can be r moved by cons Î dp r ins the simil- tani'iius production of two part i clcs, one from each proton, each particle bavin*; high momentum and small p.„. Consider as an example for which we can writu for this cum: of gluon oxch:mi:o : f> ¥• j> -i iiùddi't f- kuiê 4Ai- —, h + n* ï ^* t-sr~~ while far q exchange we would have ID —• h f- a -t- A. f. /x and for q exchange: /> -f-fr ~> tee-it ,/s efs / butt u^tj eTs e/: t ^__- 1 —» Uds + Tl* -f- Ctitieje/f i K~ (?/ We now have two momentum spectra, one in each hemisphere, characterized by (/-x) O ~*J'' J v--rn.ro J and :! are related to the number of spectators N and N_ in each hemisphere by: W-- 2f/, -I rA - it/^-f \n the above example we then have for the numbers of valence, sea and valence + sea spectators in each hemisphere: g-exchange q^-exchange qv-cxchar.ge + - + + - n = 2 n=2 n=2 n=2 n=l n=2 V V V V V V n = I n=l n = 0 n=2 n=l n=2 s s s s s s n = 3 n = 3 > n = 2 n = 4 n=2 n = i Is'ÎLh our two ways of counting spectators, Che 3-G counting rule and the valence counting rule we have for the power law dependence of the i and ~ momenLum distributions: SRODSKY-CUXION VALENCE g Is ^v S qs qv a ? et S a 6 a 6 a 3 a S 353737 333313 Thus, in double inclusive spectra 2 of the 6 possible cases are uniquely identifiable, while the 4 remaining cases have a two-fold ambiguity. We can measure the invariant double differential cross section most easily in terms of a ratio Bt'iore substituting the power law dependence into eq. (9) we note that in t»q. (6) and likewise in eq. (7) we have stuck, one pair of sea quarks to the proton producing the f , and two pairs to the proton producing I ho - . VJu could have done it the other way around also, with the result that the number of speccacors at the two sides are interchanged, i'ho spectrum is thus a sum of two terms: The single particle spectra are obtained by sticking one pair of sea quarks to the proton; they are therefore characterized by the exponent t, which, by convention, refers. LO the lowest possible jiwr.ber of pairs of sua quarks required to produce the final state. Substitution into eq. (9) then results in the correlation coefficient: Thus for the cases for which 3 = c we have tl»i' result R(*„K) -/ i.e. the spectra are uncorrclated, at all combinations of x. and x,• For a i i the momentum distributions of the two particles produced are correlated and the ratio R is a function of x and x_. The next step is to extent the considerations above to other production processus, I» doing so we classify the final states into 7 classes. Five of Lhesu classes can be produced in pp collisions, the remaining two require pion or Kaon beams. We consider the 5 pp classes first. In writing down the <*'s and ;i's for these classes one finds that the features seen in if IT ahove - 8 - persist: 1) g-exchange with the 5~G counting rule and g or q exchange with tho vnlencu counting rule both result in an absence of correlations; 2) q and q exchange with the B-G counting rule are indistinguisable, and so are g and q exchange with the valence counting rule. The resulting values of ex and 3 for the 5 pp classes have been col- looted in table J, in order of increasing number of spectators. It is immediately clear that the production of \ 's, ,\{ 1 520) ' s and " ( 1385) ' s requires only a small number of spectators ar.d therefore have spectra which extend out to high momenta. Furthermore it seems reasonable to expect that A's, A 's, -rV's» A 's(?> will all be produced with similar x-dependences: in all cases the incident proton looses one valence quark by fragmentation, Che missing quark being replaced by an s, c, b or t (?) quark from the sea. V. CONFRONT ATHON KITH EXPERIMENT Having cast the model into the simple form of table 1 we can now confront the predicted powerlaws and correlations - or their absence - with experiment Data on the momentum dependence of inclusively produced single particLe spectra are shown in fig. 10. Here values of a have been collected from 42 experiments performed by 5 teams of experimenters on 34 different reactions. The data are divided into the 7 classes mentioned above, five of which can be reached by means of proton beams or meson beams the remaining two by means of meson beams alone, Some of the recent data from which these a's were derived are shown in figs.. 11, 12 and 13. They were obtained by Block et al. with the spectro meters of fig. 2. Fig. (I shows the x—dependence of inclusive .1, .'(1520) and ç production. The a's correspond to the black points in fig. 10. Fig. 12 r shown the ratio A/A production versus x. Fig. 13 shows new data on the production of antiprotons at high x together with earlier data at x _ 0.5. I:i contrast to the wealth of data on single particle production, there ha.i been onlv one experiment on double fragmentât ion leading to two high >: final state particles in opposite fierai spa»; res. This experiment was do.ie at the ISR with the equipment of fig. 2. The reason for the scarcity of such experiments is that they are very difficult to do at fixed target accelerators. The results of the experiment on ~~ corre latiens are shown in figs. 1-, 15 and 16. Figs. 14 and 15 show the correlation coefficient X as function of x. and x? for t -• , i -* and - - pairs. Tiie striking result is a com^ p le te absence of any correlation, i.e. R = 1. Looking back at table I we see that this one experiment wipes out the cases of q or q exchange wiLti the H-G counting rule and q exchange with the valence counting rule. The case of q or q exchange with the 3-G counting rule is illustrated by the solid lines in figs. J4 and J5. Another way of naking the same point is to computer the double differential cross sect ion from the data. This is shown in fig. 16, where they are compared wi ch the computed spectra assuming no correlations, i.e. R = 1. One sees that over 5 decades in 3 ... there are no significant deviations from the K = 1 curves (solid lines in fig. 16). Taking the absence of correlations as a fact of life, one nates that the four categories of a's and z1s in table 1 are reduced to two, i.e. those for which a = S. These two cases are indicated by vertical lines in fig. 10, the dotted lines for g-exchange with the B-G counting rule, the solid lines for g or q exchange with the valence counting rule. It is then apparent that with the conbined evidence on the x-dependence en" single partiale spectra and the absence ot correlations '.JO are able no ruU' out U of the 6 cases, considered originally. Can we conclude that the remaining two, indistinguisable cases, represented by the solid lines in fig. 10, do agree with the data? There is at best global, qualitative agreement in the Jst, 3rd, bth, 5th and 6th class of reactions, wit)i notable deviations, for example p --1 TT , which is one of the best measured reactions. A puzzling exception is class 2 (meson -*- baryon, with one valence quark Boing to the final state particle) which seems to require a = 2 rather thar. J. = I as prescribed by the model. Strong deviations are also found in class 7 (p •+ p, p - A) but here we have a natural explanation. Experiments performed in 1974 at the LSR on the correlation between pairs of identified particles produced inclu sively in the same hemisphere have shown that such pairs are generally unccrrelated, with the exception of pp and K K pairs. Although forwardly produced protons need not be produced as pp pairs, antiprotons always are, as require • by baryon conservation. Similarly, K -mesons fon/ardly produced need not be accompanied by K mesons, but K -mesons are most of the time produced as K K pairs, as required by strangeness conser vation. Therefore, in p •* p and p •* A the spectator quarks are the (valence or valence + sea) quarks left over after production of the pairs pp resp. ,V.. This gives n = 3, n =0, and hence the power law for the pair is (1-x) , with the result that the pair decay products p and A £ollow-power laws with exponents a > 5. A similar situation arises for T * K but here the effect on a is less pronounced due to the smallness of the pai r mass. With the above mentioned proviso's in mind we can conclude that, in the framework of the models discussed, the experimental data are consistently disagreement with most of the proposed mechanismes of exchange, and support thu remaining alternatives. We may phrase this conclusion by saying that: The evidence en the nonentux dependence of the inclusive di fferontial cross section for the fragmentation of one or both of the incident particles into a high momentum secundary makes it plausible that: ]J fast forward secundaries are produced by the combinat ion of fast valence quarks and slow sea quarks in the initial state; 2) the res idual fractional energy, 1 -x, is shared era in i y among the remaining valence quarks, with very little going to the remaining sea quarks; 3) gluon exchange and/or sea quark exchange is the dominant means of coiri.T.ur.icatiûn between the incident part icles during the interaction. VI THE HIGH X TAIL OF THF. HIGH X. DATA Closer inspection of the high :•; tail, say x '• 0.7, of the high x low p.r data reveals that the picture sketched above is, although globally correct, incomplete and that something is still missing in our understanding of these spectra. The basic point is that although the quark momentum distributions are reasonably well described by single power laws (|-x) , the momentum dis tributions of the produced particles, being composites of quarks, are not. This is illustrated in figs. 17 and 18, which shows typical data on the production of high x n , TT , K and K mesons, in comparison with the bare quark distributions u(x), d(x), s(x), represented by the dotted lines. In fig. 17 these distributions have be^n derived from deep-inelastic e+p, e+n scattering, neutrino-induced reactions and particle production data at large p by Field and Feynman . One notes that these "experimental" quarkdistri- bution resemble simple power laws (i.e. straight lines on a log-log scale) and deviate significantly from the datapoints for x > 0.7. A different parametrization gf the quarkdistributions, by Das et al. shows very much the same result, see fig. 18. One may therefore attempt to describe the spectra by incorporating the global features as derived from the counting rulis discussed earlier into a realistic description of the particle spectra as the convolution of the (power law type) momentum spectrum of the valence quark(s) with the one or. 9) the sea quarks involved. Das and Hwa have given the following expression for the inclusive production of mesons with fractional momentum x and trans verse momentum p . AU;) TV'V^ *'-fJK) W £(K 'K "-) where q, (x) are the momentum distributions of the flavors k = u, d, s. The meson momentum is the sum of the momenta of the constituents, e.g. xx* m K + *? ('V The factor in front of the integral arises from phasespace. The spectra computed this way are shown as solid lines in figs. 17 and 18 and show (for two assumptions concerning the distributions of the down-sea quarks d , one following ref. 7, the other one with an updated d -distribution) that the discrepancy between the bare quark distribution and the data is fully explained by taking into account the effect of the sea quarks, which tend to raise the cross section at fixed x as a result of the added contribution of the sea quark momentum. Good agreement is obtained in all spectra, including K were both quarks in the final state are sea quarks. We can therefore conclude that the Das/Hwa formula, which incorporates the notions derived from the counting rules, i.e. gluon exchange and a. strongly reduced role for the yea quarks relative to Llic valence quarks (through i Ju1 difference in exponents of the x-distribut i on) £i ves a corrtet des~ cription of these experiments. Note that in rhe lirr.it the s impie power law is recovered from eq. (12). VII p + p - MESONS AT 0 , 1-2 TeV The model discussed thui far, gluon exch^nflo and the valence counting rule can be extended trivially to collisions of anti protons on protons. We have the following relations between p and p quarks: fron which it follows that: Tit-***) - />(/-**) / (f->V = />//> •->*) and similarly for other produced secundaries. Specifically we expect the \ spectrum opposite the p beam in TSR or SPS to have the form of fig. 11, "-( 1 -x) ' . This would open the possibi lit y of detecting A 's, if sufficiently intense p beams could be obtained. The symmetry between pp and pp would be broken if the exchange whore not purely g-exchange but had an admixture of q-e::change. An example is shown in fig. 19 which shows calculated p(p -*- ir ) and p(p -+ TT ) spectra for pure g-exchange (solid lines) and for g-exchange plus the maximum amount of q-exchange admitted by the pp -*• ir~ data discussed earlier (dashed lines). It is seen that the differences are small, so that also if some q-exchange is present, the relations in eq. (14) remain substantially correct. A special type of events are the events in which one of the initial protons is quasi-elastically scattered: p + p •*• p + X. Single diffraction dissocia tion is characterized by a cross section which rises slowly with s, a slope which rises with s, a da/dt which is a smoothly varying function of t, without maxima and minima, a differential cross section varying as I/M2, and scaling as M2/s. Furthermore, the multiplicity associated with a missing mass M of X varies as invariant cross section we have for the total single diffractive cross section: "L ft/..., -- >V -M. a O./ S A^tt the latter limit being the maximum missing mass which can be produced ] 2) coherently by the critérium of Good and Walker . From extensive measure- at ISR we obtain O/S as a reasonably good fit to the integrated diffractive cross section. Eq. (17) enables us to compute the integrated diffractive production M . = M . Cases of interest at TSR and SPS/collider energies are: mm x 31/3] GeV 10.1 8.7 5.4 2.1 mb 270/27/ GeV 17.6 16.2 13.0 9.6 rob These cross sections are to be multiplied by the ratios th: ft*-*u /7, 0*J which we shall now determine from experimental data. In a recent experiment A 's were diffractively produced with a cross section times branching ratio,C5, equal to: / Sv {//•• •>/>%- /* The various limits are due to aperture limits in the apparatus and cuts in the software analysis. Fig. 20 indicates the diffractive peak (different symbols indicate different ISR energies) and the limit M = 10 GeV ot this experiment as well as the threshold for A * D production. The diffractive production times decay (M -> A ) from threshold onwards is then per hemisphere, with 0.3 < x(A ) < 0.8 and Q < p (A ) < 1.0 Gev. We may relate this cross section to the inclusive cross section for /. production by noting that, at ISR energies: K ç.rtj.2 fi*/ CP Cf'f' ~* £'*?&? fcfrr(AC/Tr-Jl &wa) This gives .= S-yùé H We assume the x and p_ dependence for inclusive A production to be 4) the sane as that ror A production : Integrating this over the range 0.3 < x. < 0.8 and normalizing it to the result in eq. (22) we have A = O.0J3 mb/GeV2 (for A this is A = 1.7 rab/CeV-) The x-dependence of A production may not be representative for states of higher mass, such as A , since part of the A yield results from feed- down from decaying states of higher mass (in particular from 1(1385)/. If we take the A(1520) production as more representative for A production we get, for A : le. Le grating oq. (22) we oh tain the inclus îvc /,__ cross section (pp - .\ X) = 51 ub. With the help of eq. (21) we can then remove the restrictions on the x(\ .) and p (.'. ) ranges in eq. (20) and obtain integrated diffractive cross sections for the production of high mass states above the .\ threshold times their branching ratio for decay c into a .'. + X ' : c Comparing this with the table above ue have for the ratio in eq. (18): f-rfeji/J */c" O'-J ft* -> Acc S7v v/c> for the branching ratio for decay into a A of a diffractively produced missing mass with mass above the .'. D Repeating the calculation with the distribution of eq. (23) we obtain /% ->Au L r s We may compare this with A production where we have *T~(tt>-'f>X, font**)) fa -*AK'J = -f -/-rAf ft* -^ _££ __ c _ />„ -7 Acc. t1 p "' ? In words: diffraction dissociation leads to the coherent production of massive missing mass states. The cross section for producing missing masses above the A -production threshold mass is 5.4 mb at /s = 63 and 13 mb at c v •s = 540 GeV. In 0. 1 - 0.2 7, of the cases this mass wi'Ll decay with n A c anon g its decay products. For /» ' s the cross sections are 8. 7 and 16.2 mb and the fraction is ^ 17 %. In diffracrive events the decay products are spread over a range of rapidities which depend un the mass. At low masses all decay products are in one hemisphere, at higher masses there is spill-over into the hemisphere containing the diffractively scattered proton (as the only other particle). Fig. 21 shows the rapidity distribution of charged secundaries for various selected missing masses. These clusters have A / centres located at y = -ln-rr and edges y , = -In*s and y _ = -In s/M~ ra n el e Fcr masses close to the -'l D threshold there would be sDill-ove J. r into the c opposite hemisphere if »;s = M2 = 17 GeV". At ISR or SPS/collider energies the cluster corresponding to M = M. + M = 4.12 GeV is contained within the rapidity interval: »'s » 63 GeV 1.3 ^ y < A. 7 >'s = 540 CeV 3-5 < y < 6.3 roughly corresponding to a cone of 30 , resp. 3.5 around the beampipe of the respective colliders. Diffractive production thus has the advantage of providing an additional constraint (the missing mass as derived from the diffractively scattered proton) and of reduced background (most of 4ÏÏ is empty); the disadvantage is a loss of a factor ^ 5 in event rate compared to inclusive triggering. For given branching ratio's, acceptance, tracking and particle iden tification efficiencies eqs. (22) and (23) are useful for obtaining eventrates in a given set-up. r - n> ArKNOKXKDCI.-.'lJ^'T •A The pro h lems discussed here have beer, the subject of invest i gat ion oi a series of experiments at the CEKN'/ISR by the CERN/ilalland/Lancasrer/ Manchester and the Amstcrdam/I.ouvnin/North Western collaborating over the period 1971-1979. The author acknowledges very valuable discussions with the participants in these experiments. No attempt has been madf :;t completeness in the presentation of the material and in the listing of the references. March 1980 REFERENCES 1. Singh et al., Nucl. Phys. 3140 (1978) 139. 2. M.G. Albrou et al, Nucl. Phys. JI72 (1974) 40. 3. S.J.r.rodsky 4 J.F.Gunion. Phys.Rev. £17. (1978) 848. 4. M.M. Block et al-, CERN Repart no. CERN/EP/79-82. 5. C.J. aobbink et al., PRL 44 (1980) 118. b. M.G. Albrow et al., PL 65_B (1976) 295. 7. R.D. Field and R.P. Feynman, PR Djjj (1977) 2590. 8. F.T. Dao et al., PRL 39_ (1977) 1388. 9. K.P. Das and R.C. Hwa, Oregon University Report No. 0ITS-73, 1977. 0. F.C. Erne and J.C. Sens, CERN preprint January 1978. 1. 1). van l-'pzep, M.Sc. Thesis, University of Utrecht, The Netherlands 2. Good S Walker, Pliys.Rev.120 (1960) 1857. 3. M.C. Albrow et al., Nucl. Phys. B108 (1976) 1. 4. K.L. Giboni et al., PL 85B (1979) 437. 'COL'NTISC BKODSKY/GUNION VALENCE 1 KEEE ENERGY q AND q q ONLY s v V 'SHAKING 1 lr.XCIIA.NGE GLEO.N , q OR q 1 GLUON OH qs q„ 1 i .'. j ; S | '. fl A(15JO) :*U385) 3 3 1 5 1 I 1 3 5 5 3 7 3 3 1 3| ::~ CI385) 7 7 5 9 3 3 1 5 K~ 9 9 7 11 5 5 3 7 Â,P 11 11 9 13 5 5 3 7 (UNCORRELATED) ( u '*»£ "VaR* Cm.Mni.RS WIRE SPAfl* CHAMBERS JI-4 C) ^BM3 HM? BMT fi F C2 E Cl D / SEPT •JfpT~~^| BARREL FOflWARD "M BC . j I 1 I ] \ 1 11/ MA&NET MAG\fl DETECTOR DETECTOR M0M ^N SPARK H^^^pQEEHHfcr^1 LJ U U ^H LUMMON CROSSING I * i :.—,.._.^-C NUMBER 5 ica;i ii i—in JWTJO^i Fig. 1 I, 5 m. MOMENTUM SFECTRUM GKP RÔO^ Fis.3 t T 1 i r TC*" COMPARISON OF INVARIANT CROSS-SECTION AT p = 0-75 GeV 10' I o A O iro TJ|*U LU Iff ,-1 10' 0-4 0-7 0-8 0-9 1-0 Fits- 7s 10 —I r— pp—- p»... it x = 0.6 10 V /F IGeV) dJo- • 31.0") (mb.GeV'•îl| X dp3 « 45.0 CHLM « 53.2 10" \ • 62.6. 6.8 ALLABY ET Is s \ io-2- Mf 4\ V.t\ 1i \ 10" MM 1 \1 •• \ \ 10" p (GeV)- -5 10 -J I I 1 L_ ' ' i_ 0.4 0.6 0.8 1.0 1.2 1A 1.6 1.8 2.0 2.2 2A Fig. 5 0-4 0.5 06 0-7 0-8 0-9 1-0 A 04 0-5 06 07 0-8 0-9 10 Fig.7 r r PT= 0-55 GeV ' " \ p + p—*TC~+X • d (x) text) 10'- CM I > O co i a 10 w 10' -1 10 0-4 0-5 0-6 0-7 0-8 0-9 1-0 L i 1 1 1 1 r 50 20 100- 1-0 50- 05 20- 0-2 10- 1-0 irvTf 0-5 0-2 X » _j i i i i 1_ .J L. J L 0-5 0-6 0-7 0-8 0-9 10 Fif, .9 0-5 0-6 07 0-8 09 1-0 r 71 -- rC 4- Smçh et cl -"- K" K+~77+ û Edwards et ci K" — 71" v Erhan et al p - A r^*" • Block et al A P — '!;20 o Cutis et al P -*IMS ÏT+— p 71"—? TT.+ — p ti"— p K+-p K'—p it"— n it"—A TT-A p -n* p -r.; p — A P — •"-" P -71+ TI+-TI- 71"- 71+ TI+-K~ -o- R--K+ -o- K+-7C- K~—1+ K+- ir K"—K+ P -Irâ K~-p p -K" p —P p -A i "i l i i i l l [- rA'.X s = 3880 GeV2 p+p_ A°(i520) + X p 0-65 GeV/c i(jl{102û)*X f T-- ExP R607 a 10 xi • tits with A (l-x)n A°:i520 10 n = 0.810.2 s 10 (j)(l02CXx!0) | n = 2.410.9 .-A 10 0-4 06 10 FiR.11 1 I 1 1 1 r PARTICLE RATIO P • P —• Â= . X p. p A° . X 10 10 -V ^ A/A A(1-x)r A=1.0310.26 ,3 10 n = 84-04 +. 10 A RS07 s =3880 GeV' + H.KICHIMI et al , s=750 CeMz 10" J l_ L J I \.. I 0.2 0.4 0.6 fig. 12 —[ 1 p-+p *p + X x O ref. 2 Vs. 53 GeV V A ref.i El=l75GeV V ref 5 Vs = 63 GeV D ref. 6 Vs = 53GeV • R607 Vs=63GeV -100 P = 0.5 GeV/c N t r^ \\ > — A(1 -x) O -10 v} n - 8.2^0.2 \ -Q \\ ^ \\ na P|a A(! -x)n,+ B(1-x ) \ -bi-o 8.9i0-2 LU n,- n = 2.010.5 1 2 vv V » i 1 \ T 02 0 06 —x-»- Fig.l3 • TC*Tt* O TTTTt* X Tt" Tî" 0 o o o o o 1.0 .ftfcJXiS-t 0.5 0.2 R 0 J L _[ I _%&. $_9_ o o o o o ^ 1.0 *_i_9 i-r î 0.5 i 0.4 _L _i_ 0.4 0.6 0.8 1.0 0.4 0.6 0.8 1.0 • TT*Tt* 0 Tt"TC* X TI" TI" o o o o o ^ 0 0 0 0^1 1 0.5 t 0.6 0.8 n 0.4 0.6 0.8 1.0 9 in 3 Fig.16 i—i r i r FIELD FEYNMAN q(x) C(qq,x) C(qq,x).d„a = 0.15(l-x)'°/x Data J. Singh et al. Réf. 1 100 100 • 1.0 • 1.0r 0.1 • oou 0.5 C.6 0.7 Fis.17 T r DAO et al. q(x) C(qq.x) C(qq,x),sea = 017(1-x),0/x Data J. Singh et al. Ret 1 100 — 100- 1-C m J 5 "Vz~ 10 r- K 1.0- i I C(sû,x) N ^<^' 0.1 s(x) 001L 0.5 0.6 0.7 03 0.85 0.90 0.S5 x —- Fin.I8 «•-PHGaicTiomrDfnuji-riQ.01 n'-piîOoucTiœiiFmavM-ru:!.!)) .6 .£ .4 î -r .1 .OG.OS.04 .02 -02 ex .t .i -2 .i -fls.occ» -113 -a: 1 Tfrnn—r |rrrr-p' i—i 1— \ —-nil tschanflO — -r.o «alicnfle -Jt-"ïllh exchauflc -"—vfLh L-zchsiige LootlnQ upstream p-beam Lotiktnu upstream p -beara \ r ; V r v X : .aat 1 l l l I i_i L_ 11 i ) i i i I L ]C.0jlJ-U.I I I -C .C .« -3 .2 .05.0* .03 .DZ .6 .5 .* -Î -I -1 .CE.Ct.Ot .01 .02 FLK.19 T" "b/FfiTACT/ùf/ 3/SSûC/ATA'Û/' t \ ^? Vs=ésça/ %£cé y&KZSJfati* *k|iov_Q/-is.^ o ^^^^v^* X<2S?1I L. 0 0.05 0.10 M2/s Fig.20 DIFFRACTIVE EXCITATION AND ASSOCIATED CORRELATIONS • HIGH MOMENTUM PART OF THE INELASTIC, INCLUSIVE PROTON SPECTRUM s = 934 GeV2 t = -0.3 (GeV/c)2 _4 _3 _2 | |-1| 0 1 2 3 A v=-\nJE for M2 = 12,28,68 GeV2 ~ "H-*" £ M ?lg.21 CERN/EP 29 May 1980 EXPERIMENTAL REVIEW OF CHARM HADROPRODUCTION W.M. Geist CERN, Geneva, Switzerland Invited Talk at the Workshop on the Production of High Mass Flavours Paris, November 1979 (•') Now at Institut fur Hochenergiephysik der Universitat Heidelberg, Germany. 0032R/WMG/ed . INTRODUCTION This is a brief summary of all relevant experimental evidence for charm production by proton beams. Theoretical models will not be mentioned because of the following reason: current models usually deal only with central production and predict small inclusive charm cross sections. As it will be shown below, the experiments find, however, large cross sections with substantial contributions in the forward direction. So there seems to be little overlap. In sect. 2 some recently measured charmed particle properties are collected. Consequences for experiments and for the evaluation of cross sections from the measurements to be described in sect. 3 are discussed as well. From a comparison of all (differential) cross sections obtained so tar, a crude picture of charm production emerges in sect. A. 2. AN EXCERPT OF CHARMED PARTICLE PROPERTIES 2 . 1 Charmed baryon A,. 2.1.1 Mass At SLAC the A mass was determined to be c iy- = 2285 + 6 MeV il], c whereas in a neutrino bubble chamber experiment m+ = 2257 + 10 MeV [2) was found. Ac The A masses measured at the ISR (sects 3.3(b) and 3.5(a)) are between c + these limits. This means that the correct A mass is not vet known. c J 2.1.2 Branching ratios From the SLAC A data the branching ratio B(A -*• K n p) was calculated from the relation + B(Ac •* pX) w T\u: inci cross section 0(A D) was measured as we 1 • as 'J . . Furthermore it was assumed that 60% of all A decav into protons, i.e. ${•'• • p.\) = Q.h ami that the full step -'-Rfp) of tin.- inclusive proton yield Jtn» tn - production; this holds onlv if 1(!\ D p) •'< "( :'. .'. ) and c c . °+ - + m-++ - m,+ •' n_.. Those assumptions tend to minimize? IH.L, - K - p) and SI-"- - K ' p) = (2.2 + 1.0)%. c r — A v.il ui' ni "- •'*% can certainly not be ru ted out. Pre 1iminary re su 1 ts on résonance con tribut ions to this branching ratio have been shown rocently |3| (s.'e also soct. J.3(a)). lit.'. , - K p) B(A K ) + 3(.". - K~- *p) BC.'i t - K ""p) Unfortunately nei ther the semileptonic brunch in g ratio of th« -• nor the corresponding lepton spectrum are known. 2.2 Charmed mesons 2.2.1 Semileptonic branching ratios A very surprising finding was that the semileptonic branching rat ios for charged and neutral D mesons are different + Bsl(D ~ eX) = (23 + b)% [A] , (15.8 + 5.3)* [5] , H |(D°- eX) •• h% JM , (5.1 + 3.3)2 (5J. Implicat ions wi11 be d iscussed in sec t. 3.1. 2.2.2 Exc Ixisi ve branch i ng ratios B, E n Sone exclusive branching ratios for the lowest final state mo 11 ipi ic it ii;s are 1 is ted in table 1. 2 . i Consequi-ncf s From the different values of the semileptonic branching ratios of D- and D and tiin unknown semileptonic i\ branch ing ratio it c follows that experiments which measure the lepton flux from senileptonic char mi» J par t ic le decays cannot con tri bute very much co a de ta £ led understanding of hadronic charm production (see sect. 3.1). So the cleanest way to study charm production dynamics is to detect hadronic charm decays. Now one knows from sects 2.1.2 and 2.2.2 that hadronic exclusive br.incning ratios for charmed particles are rather small, typically in the order of 2% to !>%. From small branching ratios and presumably fairly small inclusive cross sections one expects a high combinatorial background when looking ac effective mass distributions. To find significant signals this background has to be suppressed. This has been achieved so far {sect. 3) by: (a) Very selective triggers and/or (b) K , p identification and/or t c ) V reconstruction and/or (d) measuring the full event. 3. EXPERIMENTAI. RESULTS Here only non-emulsion experiments will be reviewed which show significant evidence for charm production in p-nucleon interactions at cm. energies /s > 20 GeV. The relevant experiments - with emphasis on the ISR - are classified according to the types of (double) inclusive charmed particle production and decays to which they are sensitive. Some attention will be payed to the uncertainties affecting experimental charm cross sect ions ; for technical details and problems the original publications should be consul ted. Throughout N, C, 1, h denote a nucléon, a charmed particle (baryon or meson), a lepton and the decay products from a hadronic C decay; additional C ' ) particles are symbolized by X . E, p, x and p are the energy, three- momentum, Peynman variable and transverse momentum of a particle in the cm. s. 3.1 Prompt single lepton production Charmed particles are the source of a single lepton flux produced in the react ion NN+C+X , 1 = v, U, e. '•->• 1 + X' r Expérimenta I ly the s i ngl e prompt ) opt on f 1 ;ix is doto. mine.: a? :he ox cos s u vof .1 ( largo) iepCon r lux from convent: ionnl sources , i.e. ( seni - ) 1 optonic ( voceor) mesun and baryon decjys and the lepton pai r conG nviim. In case 01" fleet run detection there are in addition contributions from (Li'.npl.in processes and '•-conversions in the apparatus. T;io mo=[ siri>n:s iirjjkiriiîir.iis are nit h or suppressed by vetci ng 'in case of electron expor îments ) or by dumping (in case of u or \> detection in beam dump ox per 1 monts ) par t ic les with 1 i fet imes larger than '^ 10 s before thoy can decay. The remain 1ng background fluxes are then subtracted by Monte-Carlo methods far which one has to know the production spectra Car all conLribut i ng sources (see e.g. (6]>. Thus it is not excluded chat results from experiments of tins kind contain fairiy large systematical errors. Having cst3bl ished a sing i e prompt lepton flu.x, a cross section for C production can be obtained (assuming all leptons are due to C decays) from the re 1ation: [.epton cross section « |>1(C) [ ~(g) d!" . B (C) . ™ ~© Mere the unknown matrix clement for inclusive C production M(C) is convoluted with the lepton decay spectrum dT in the C rest Crame. The latter is not sufficiently precisely measured tor all purposes. Especially at tin» high energy tail the shape of d" is influenced by the assumed T cross section [7|. Examples for the influence of the shape of dT on the predicted leptui', fluxes wilt be given below. J - 48 - A complete analysis of single prompt lepton data would require a fit of the following expression to the data: a (p x) Z 0 Lepton cross section « A l T' |M(D°) I Q aTpo . B^tD ) * Aa3(pT'x)iM(,'.'f)|2©dr,+ B , whore A "i "T1"' gives the atomic number dependence for charmed particLe production on nuclear targets; o. ft* 0.9 * 1.0 can be guessed for m _ « 2 GeV from the measured mass dependence oE PL [81 , Si nee in the above formula only B (D ), B . (D ) and ( J" J + (JT + J are known, the evaluation of charm cross sec t ions I'r.mi single lepton experimencs is rather unsafe. i C a) Beam dump experiments [9]- Cross sections sad the assumptions made to derive them as well as single prompt lepton to pion ratios are listed in table 2 for Li- and v-beam dump experiments. All cross sections calculated from the data assuming central production mechanisms, a semiteptonic branching ratio of ^103 and a linear A dependence are in the order of 10 * 60 Ub/N. The single prompt lepton to pion ratio measured with heavy targets is in chu range 5 5 2 . 10~ * ± (x £ 0.1, pT £0.8 GeV/c) £ 4 . 10" |9]. From fig. 1 one concludes that a central charm production mechanism E -j^-(U) = (1 - x)J (solid line) does not describe the x-dependence of dp ;./" as determined by [9(a)) very well. The dashed line shows the prediction I mm d.3/dy(U) = const, witli a \i spectrum in the D rest frame which corresponds to a * (ft) * 00/1 admixture of K to the decays D •*• |JK \J. Increasing the K contribution to 100% one finds the dotted curve 110}. Contrary to common believe tlie neutrino energy distribution displayed in |y(d)J cannot ruîe out charm production mechanisms which hnvo a wi.-.ii(i-i* :%-dependenco than { 1 - xj I 101 . ( !> ) S î:rj It? prompt el iKtron product ion Sir.ulo t'k^crons produced at i's = 33 G^V at a polar an^le ". . = 30' wt-ri' ra,;,-isiirt-'J by the AC'.IWR Collaboration 111). The resulting e/ as a i une t i.ir, m p is displayed in f ifl. 2 . The on! y unsubtrac ted hac! Inclusive D cross sections in the order of 130 ;.b to 320 ..b cm be deduced from these u.-jt.i 1 10 I . 3 .2 IncI us iva product ion of lepton-antilepton pairs Tile next type of experiment one may consider is sensitive to CÇ produc t i on with subsequent semileptonic decays of both charmed particles in til- react ion: NN " CC + X , 11 = ee , en , W , Similar to the above single lepton case the e V flux due to short lived sources is defined as the excess above the measured e P -flux, in case of electron pairs the background due to (vector) mesons is subtracted hy Monte-Carlo methods- From the lepton pair flux a CC production cross section can be derived via the relation: U cross section a |M(CC)|2® dr2 B2,(C), CC = DD, DA+, A+.\+ v si c c c ~W ~® Uncertainties due to the semileptonic C decays (cT, B ,) come in * si twice. In addition one has to find the correct parametrization for the ;natr i x element M(CC) for Cun-)correlated charmed particle pair production. (.i) At FNAL a CALTECH-Stanford experiment [12] measured the missing energy E . in the reaction pFe •* 1- P X at 40Q GeV/c with a total absorption calorimeter. Assuming dN/dE . = dN/d(E , + E - ) , _ _ miss ._ Vl V£ E —{-) « (1/MJ)(l - xr* pTe"yM/>s, (M = M(DD), a = t.3 f 2.7, (3 = 2 r 6 dp DD Ï ~ 20), B(D •* UX) = BX and a linear A dependence of the inclusive DD cross (b) At the ÏSR the CERN-Saclay-ETH Collaboration [13J measured e e and ej pairs emitted at x ra 0 with a 3-arm spectrometer (fig. 3). Data vvvre taken at /s = 52 and 63 GeV in the three configurations sketched below in the azimuthal plane: r p p(e)Z. 0.6 6cV/c f (e*+e-)>, Z.3 G«% p (a) X 0.6 GeVfc The di. fieront set-ups were used to determine the p dependence of ! -in ) corn1 i a ted DD product ion at x » 0 from the daca. Because of the cuts .it r.pi ther hi u:i lepton momenta the resulting cross sections are, hoi*.1 ver, verv sensitive to the shape of the high energy tail of the lepton n poet rum in tin' D rest frame. Wi th .i central product ion mode 1 and a semi 1eptoni c branch i ni; ratio or" li)j t.ie d i f forent iaI cross sect ion was determined: 1 r • n(DÏ = (10 - 2.3Kb. Note that the cross section might be higher by a factor RJ 3 i f 1)' dominate in the central region. This could be true if most of Lho l> mesn:v; are , 1 iki- pi on s, decay products of vector mesons _i. J : --.L' 1.1.s i ve mul t ir.adron produc t ion !'iist c h Jim searches were performed by look i:-.f> for hadroni r decays of cn.irni'il parLicies produced in the reaction - h A.1) a 1 ready ment ioned in sec t. 2 . J the comb î nator i a 1 background is r.'iLlu-r h iyh wlwn look iny for structures in effective mass distributions of liadrons so that most of tlie.se experiments were unsuccessful; they are not discussed here (see e.g. [ 10 I for references). Recently, two experiment^ rr.in.i^ou to abserve significant signals. Trie proof that the decav.s or £ |4 ir.at-'d from a charmed parc ic le is obtained from the exotic quantum numbers ui the decay products and/or the width of mo i r e fleet i ve mass distribution. The inclusive C cross section is determined from the rehitio (••••) Bfl> - 1) ]• » B(I) - I) ) (see j.:> [ ]i] ) . o © (a) The CCHK Collaboration was the first to observe charmed particle (D ) production in hadronic reactions [15]. This experiment was performed with the SFM by triggering on identified K at 5 = 8° at t's = 53 GeV. The top view of the experimental set-up is shown in fig. 4. Because of this trigger the experiment is clearly only sensitive to forward charm production. In order to further enhance this effect events of "diftractive" signature have been selected. No signal in the K ir mass distribution was found. The K TT TT mass distribution is shown in fig. 5. There is no obvious D enhancement. A study of the K i mass distribution for slices of the K r r mass reveals the strong K contribution for m(K r. 7. ) f=a m(D ) in fig. 6. Requiring therefore a K ir mass in the K region one finds the D signal of about 92 events above background (dashed line) in fig. 7. A by-product at this procedure is the relative branching ratio 7+ 0.2 - 0.2 which is larger than that found at SLAC [3,17]. The width of the D peak is consistent with the detector resolution; the difference between the measured D mass (*** 1.92 GeV) and the expected value is explained by local experimental uncertainties. The observed signal is confined to the rapidity interval y = 2 * 3 for which a cross section dJ/dy(D ) = 40 * 85 lib is calculated (see table 3 for details). An extrapolation of this cross section to full phase space can only be made consistent with the e/ir result (sect. 3.1(b)) and the lepton pair measurements (sect. 3.2(b)) if da/dy(D ) = const, or do/dx(D+) = const. is assumed [10]; the final inclusive cross sections are then 0(D*) = 390 ub or o(D+) " 210 [jb (table 3). All quoted cross sections contain a ft* 30% correction for topological cuts and are affected with a + systematical error of ** 60%. If ^ selection criteria gave significant evidence for Ac production ( fig. 8) [18]; it was detected by its decay into K p; the proton was not identified. Tiie peak centered at 2.26 GeV contains 28 events above background (dashed line) and corresponds to Feynman x between 0.3 and 0.8. Since th.: quantum number of the K p system are not exotic, the proof that tin? signal is due to a charmed baryon is based upon its width which is consistent with the experimental resolution. With the parametr iz.it ion P + d" :/tixdp~ f.'.J ** L'"" T one finds: B( Ac -* K~" p)dO/d:< = -'t.75. -b and "('•*) = 375 -b, where 3( \* - K"p)/B(;\* - K~'-+p> = O-^o'i f compare with soct. 2.1.2) has been determined from tho data [16] ami B(A_ -K ' p) = 2.2T; (s.'cc. 'J.Kb)). Again all cross sections contain a a* 30% correction for topological cuts and thus represent fully inclusive cross sections; thfc fivpurLmontal errors are « 4QÂ. (b) The UCLA-Sac lav Collaboration measured inclusive A production at is = 3 c r and b3 GeV [19] with the double septum magnet spectrometer shown in fie.. 9. K p nass distributions and Ai (3") mass distributions (fig. 10) from ovcr.es with Cerenkov identified K and reconstructed A were invest igated. A;- excès of about 30 events above background at the A mass, which was uu'asurec! to be 22SO _+ 7 .MeV, was observed (fig. 10(c)). The narrow widtii oE the peak surges that it is due to a ciiarmed baryon. Because of detector acceptance the iticlu A cross secLion was only measured for 0.75 C x(A ) c 0.9: c c 0.9 B(A+ - A°(3-)+) / ^ dx = (2.8 + l.0)Ub .75 dx 0.9 B(A+ - K~" p) : ~ d-A = (2.3 + 0.3) With IHA* - K_-r + p) =2.2% (sect. 2.1.2) and the asssumption that 1,4 Inclusive production of roultihadron systems in association with a lepton Experimentally one triggers on single leptons in order to suppress most of the non-charm events when looking for a hadronic charmed particle decay in the reaction NN •*• Ct + C2 + X, e.g.: PP •* D°D°X LLh. lL-*-x' Evidence fjr charmed particle production comes for studying effective mass distributions; the quantum numbers of the multihadron system h have t be exotic and/or an eventual mass peak has to have a narrow width. Also, the quantum numbers of the hadrons and the charge of the lepton have to be correlated like in the above example. Once a signal is established the cross section is determined from the relation: - 2 - Number ol events above background = |M(CC)| a dr B ,(C) B, (C). v si h Again one has to arbitrarily chose a suitable matrix element M(CC) for (un)correlated CC production and the value of B ,(0. (a) The ACCDNW Collaboration performed an experiment of the above type with the upgraded SFM (fig. 11) at *s = 63 GeV by triggering on electrons emitted at a polar angle of«90° [18]. The electrons were identified by a coincidence of two Cerenkov signals, narrow angle electron pairs from Dalttz decays of •'•" and n were rejected off-line on the basis of pulse height information from a MWPC with analogue read-out. From e~ triggered events with a diffractive signature the K ^ p mass distribution of fig. 12 was found, which shows an ^ 65 event excess above a smooth background from event mixing; another structureless bnckgroond from e events is given in the insert. The position of the peak, the narrow width .in J the correlation with the trigger charge prove unambiguous] y that the signal is due to -'"' production and decay. With these data it was verified that B(A+ -K"p)/B(A* ~K~"*p) ^O.A (sect. 3.3(a)). From a model incorporating uncorrelated !>'• production in the 1'oLlowing way: 2 + 2? E f (5) « (1 - X>V PT, -£-L (/:) . -" T. Z an in. -(.'*) = (380 + 150) Ub is determined as well as dc/dx(.M = (5.03 + 2.5)i:b tor |x(A+)| S 0.3 (do/dx = const, for both D and — c + \* would give dc/dx (A*) « 2Ù ub an.i o(.'l ) = (1330 + 9â0);jl»î) [-<-']. c b c c - In the same experiment about 200 D decays into K were found in e~ trigger events. This corresponds to a(D°) ^ (400 t 130)ub ant! dT.'dy = (6.5 + 2.3)l.b for |y| < 0.5, if dd/dy (D°, D) = const, is assumed [21]. 3.5 Inclusive production of multihadron systems in association with a single hadron The last type of reactions discussed here is NN - U + C + X , H = p, ifr, V° ... ^ h ("•'') The particles were not identified in this analysis. Like in the two previous cases evidence for charm production and decay comes from the observation of narrow peaks in effective mass distributions and eventually from exotic quantum number of the hadronic systems studied. Cross sections are determined from the relation: 2 Number of events above background **" )M(H, C) I B, , where M(H,C) contains the unknown correlation between the particles H and C. (a) The ACHMNR Collaboration used the Lamp shade Magnet shown in fig. 13 to trigger on diffractively produced protons in the reaction pp -- pX at /s = 63 GeV and searched for A production in the recoiling system X with 10 i VL $ 28 GeV [22]. K p mass distributions are shown in fig. 14; K were identified by threshold Cerenkov counters. About 100 events above background were observed at the A mass, which was c measured to be (2260 •* 14)MeV. The width of the peak is consistent with the experimental resolution, hence one concludes that it is due to A+ c decays. and L0 $ VL $ 28 GeV is estimated to be B(A* + KV ) ^da = (3.1 + 1.6)pb [23], P dx SUMMARY AND CONCLUSIONS All measurements of the differential cross section for D production at the ISR (/s = 53, 63 GeV) are compiled in fig. 15(a). The data seem to indicate that da/dy «const, for inclusive D production. The (low) cross section from lepton pairs suffers most from model dependence (sect. 3.2). The D and D data are replotted in fig. 15(b) together with the inclusive K spectrum [24] (solid line). The x dependence of K and D-meson production is obviously very different whereas one would expect similar features since neither K~ nor D-mesons have any valence quark in common with the incoming protons. The observed trend could either be explained by contributions to D production both from central, and from diffractive production (N - MDD) or by 3 recombination mechanism of the type sketched below which produces a baryonic state B decaying charmed or bottom, quark. BQ-D •Q •Q Na •+» Fig. 16 shows the s dependence of inclusive D cross sections compiled in sect. 3. Note that the cross sections from XSR experiments have been recalculated with die parametrization 2 (D) - P-T HO) dydp" furthermore it was assumed that 0(D) = 2o(D°) = 2o(D+), A definite strong rise of the cross section between SPS/FNAL and ISR energies is Fig. 17 summarizes the irieasurements of the differential cros section for A^ production at /s = 53 and 63 GeV. Three different parametrizations for the x dependence of A* production const., E — « (1 dy dp *r are also shown. Even if the experimental cross sections differ by factors up to A, one can certainly exclude central production mechanisms. In contrast to the D-meson case this is not surprising since so far rather weak x dependences were found for baryon production. As examples, fig* 1? shows the inclusive A (L115) and A (1520) yields measured in [25] but scaled down by a factor pa 0.02. Integrated incLusive A„ cross sections have also been added to fig. 16. Both 0(D) and a(A ) are in the order of a few hundred "jb at the ISR. As already mentioned several times cross section for charm production still suffer from strong model dependence. Fig. 18 shows the s dependence of a quantity related to charm production which is much less model dependent: the single prompt lepton to pion ratio l/~i, where 1 = v[9(d)], P 19(b)! or e [11], for free nucléon targets. One has the relation V- (x «0) « 3 .c ^-l(charm), eff dxx«0 where B ff: is the effective semileptonic branching ratio averaged over all charmed sources at x «a 0; it is probably a good assumption that B .f is not a strong function of /s. Since various sources, like e.g. '^, contribute to the 1/^ ratio only values of 1/T ratios should be compared which were measured at a value of p_ where semileptonic charmed particle decays dominate decays of other particles ; this is at p «0.5 GeV/c. The measured 1/^r ratios have been corrected by the relative atomic number dependence of charm and pion production (w A /A * ) to get the values for free nucléon targets. The actual values of the various 1/TT ratios should be taken with some care since their experimental determination is not at all trivial. This compilation suggests a non-negligible s dependence, which is of course only a reflecLÎon of the s dependence of inclusive charm production, but independent of the uncertain extrapolation to full phase space. An extrapolation gives — (x ra 0, -4 PT «0.5 GeV/c) = 3 * 6 . lu at i^s = 63 GeV. Three essential points emerge from analyzing all data on charm production available up to now; (a) The pub I iahed cross sect ions are effected wi tli uncercaint ies of factors in the order of or larger than 3 depending on the type of experiment. This is partly due to purely experiment.nl problems, partly due to the lack of knowledge concerning production mechanisms. : (bj The inclusive charm cross sections are in the order of 20 " "">0 _b rsz. SPS/FNAL, energies and of a few hundred ub in the TSlî erurrgy mnn». (c) There is a substantial contr ibncion to the inclus ivn cluirm cross section from E or ward production, a process wh i cii is not vet we 11 understood, particularly in the D meson case. It is obvious that more work on the experiment.il side (differential cross sect ion with smal 1er errors and correlations between cliarmed particles) as well as on the theoretical side has to be done. Presentlv die ISR se ens to be the best place to study charm product ion in sume u>tai 1 After all, the characteristics of charm production inav serve as a guide line for future experiments search ing for heavier flavours. - 60 - REFERENCES 111 G.S. Abrams et al., SLAC-PUB-2406. [21 C. lîaltay et al., Phys. Rev. Lett. 42 (1979) 1721. •J] J. Kirkby. 1979 Int. Symposium on Lepton and Photon Interaction Hi^ii Energy, Batavia, Illinois, August 1979. ['•'. 1 DF.LCO experiment, qi Jted in !3]. |3| Vera Luth, SLAC-PUB-2405. l-il H. Wachsmuth, CERN/EP 79-125. i?i W. Bacino et al., Phys. Rev. Lett. 43 (1979) 1073. isl J.G. Branson et al-, Phys. Rev. Lett. 33 (1977) 1334. 191 (a) J.G. Branson et al., Phys. Rev. D20 (1979) 337; (b) K.w. Brown et al., Phys. Rev. Lett. 43 (1979) 410; (c) J.L. Ritchie et al., Phys. Rev. Lett. 44 (1980) 230; (dj [1. '.^achsmuth, Preliminary results from the 1979 CERN beam experiments are given in CERN/E? 79-115. |10| W.M. Geist, CERN/EP 79-78. 1111 M. Barone et al., Nucl. Phys. B132 (1978) 29. I12| A. Diamant-Berger et al., SLAC-PUB-2389. 1131 A. Chilir.garov et al., Phys. Lett. 83B (1979) 136. 114 1 See e.g. B.H. Wiik and G. Wolf, DESY 78/23. 1151 D. Drijard et al., Phys. Lett. 81B (1979) 250. lid] E.E. Kluge, CERN/EP 79-153. 1171 J.E. Kiss et al., phys. Rev. Lett. 37 (1976) 1531. 1181 D. Drijard et al., Phys. Lett. 85B (1979) 452. 1191 W. Lockman et al., Phys. Lett. 85B (1979) 443. 1201 ACCDHW Collaboration, Preliminary results, G. Sajot, Ph.D. thes Paris, in preparation. 1^1! ACCDfW Coi Liberation, preliminary results. 122] K.L. Giboni et al., Phys. Lett. 85B (1979) 437. 1231 F. Muller, private communication. |2'<| J. Singh et al., Nucl. Phys. B140 (1978) 139; M.M. Block et al., CERN/EP 79-82. 1251 S. Erlian et al., Phys. Lett. 85B (1979) 447. Exclusive D branching ratios for U dronic decays LCW D :cay Mklt |5J t (quoted in 131) D* - if"* !:.! + 0.6)2 (2.8 + 0.5)2 -(JO - (2.1 + 0. K--* " (u.o + o.d);; (6.3 * 2.2).'; D+ - K° + ( i. 5 ^ o. r. ) ;: (2.1 + 0.5)2 .,-_•.* Ci.9 j^ 1.0).! (5.2 + 1.0)': ' ÏV-. - (lj.à + 1.5)?, ' J - 62 - TABLE 2 Summary of beam dump experiments Cross section w- Ref. Reaction ! Model Ub measurod < 59 <*' '4 (X » 0.1) - , I9(a)l pCu - UX E £d p (D)« at 400 GeV/c (1 - x)V2'5 "T (4+2) . 10"5 O-A1 E ¥ (") « (1 - x)5 dp °T = 100 mb B , =10% (a) 7*10 1101 5l 13 * 60 19(b)) pFe » i-X *¥dp 3 a at 400 GeV/c (1 - x) e- PT S > 3 a = 2 * 3.5 a «A1 B„ - I0Z 19(c)] pFe -» jX 22 + 9 - (x a 0, p e> 0.3 GeV/c) at 350 GeV/c (l-xiV^T = (3.3 i 1.7) • 10"3 B > 3 a = 2 t 3.5 a- A1 B , =8% si (9(d)) pCu -+ vX 9 * 30 - Cx ra 0.1, p small) E£dp (D) « + T at 400 GeV/c (1 - x)V2pT - (1.7 + 0.7) . 10"5 (BEBC, CHARM, 0 * A1 (BEBC) CDHS) Bsl - 10% Cross sections lor D+ production at /s = 5T GeV I15| dc dy -2?T B(D * K 0.3 [•Jbl I -I. I BfD - K " " ) 3fD* • K""*'*) •= 5.23 of ^- . (1 - *>J FtCUPvE CAPTIONS Ratio of prompt single U to pion flux as function of Feynman x from a pCu experiment at 4Û0 GeV/c [9(a)]. The curves correspond 3 113 E da/dp (D) °- ( 1 - x) (solid line), do/dy (D) - const. (dashed line), assuming B(D -*• eK v) = 6% in both cases and do/dy (D) = const, with B{D •* eK^v) = 102 (dotted line). The e/ '.' ratio as function of pT, measured ac /s = 53 GeV and 30°. The solid line is calculated from 'Jlab : Œ dj/dydpT (D) e "r, the clashed line corresponds to dc/dydp^ v.D) Œ e" " PT, assuming B(D •* eK"v) = 6% in both cases; the dotted curve represents the prediction from dj/dydp" (D) Œ e~PT with B(D •+• eK y) = 102. The normalization is B(D "*• ^X)C = 0.. . 10 [10]. The crosses show the contribution from a, .J and Fig. 3 The 3-arm spectrometer used by the CERN-Saclay-ETH Collaboration. Fig. -U Top view of the original Split Field Magnet. Fig. 5 K Fi^. b K" '•* mass distribution for m(K~TT+n+) = (1.83 + O.DGeV from selected events. FIR. 7 K ' fi mass combination from selected events with the condition + that m(K"*Ji ) = (.896 + -06)GeV. The broken line shows an estimate of the background. Fig. 8 K pr mass distribution from selected events with the condition that m(K~:r+) = (0.896 + O.OOGeV. The broken line represents an estimate of the background. Fig. 9 Set-up used by the UCLA-Saclay Collaboration. - f>5 - FfCXRE CAPTLONS Cont'd) Fiy. 10 Ca) .'. invariant mass signal. (b) i nvar iant mass dis tribu t ions . invariant -ass disrr ibut LOT.s ( d ) Sum of K p' and .'. Ci') invariant mass J Lstribut ions. Fij, ii Top view or' the upgraded 5FM. F i 4. 1- K p mass d is tribut ion from events wi th an e tr i "ger . The broken I ine is an estimate of the background. The insert shows the K p" mass distr ibut ion from e events. Fiy. ij Tbe experimental set-up used by the AOHMNR Collaboration. F ; p,t 1- K p~ mass dis tr ibut ions, the insert shows a K pi nass d i stribut ion for an espec ial1 y wel1 measured subset of the data. Fi?, 15 (a) Compilation of the measured values of d-/tly (D , D ); the curve corresponds to dj/dy = const. Fig, lb Compilation of a(D) (circles) and (A ) (crosses). Fi^- I? Compi iat ion of the measured va] ues of dJ/dx (.', ) , The curves give the predictions from the models: i" J'/dpC.*) .< (1 - x)3 (dotted line), ds/dv (A+) = c • c const, (dashed line) and dJ/dx (A ) = const, (solid line). c Also shown are the measurements of dJ/dx (A ) and d~/ d:< (-'.°( 1520) ) scaled down by n factor »0.02. 18 Ci:mpi latian of single prompt lepton to pion ratios measured at x sa 0 and pT £3 0.3 CeV/c. Tn case of experiments with heavy targets the relative atomic number dependence for pion and n-nieson production lias been corrected for. -i—i—rp—i—i—i—i—I—i—i—r w i . is = 53 GeV I [111 10 o.-i\—'—i i—i i—i i—i i i i—i— O-o 0.5 1-0 FIG. 3 I 1m _l 2,2 2,6 3,0 3,4 MK-7rV+ (GeV> M(K~n*n+)= -1-88S O.I GeV -ISO K*WO) fl n L •A 1 IP] £ fl S 100 - +- Jy o 1 © St rM l/ 1] 50 \ 'LIto -/.J M (*,'**) (&t.V) Number of combinations / 80 MeV 7^ I 1 r pp - p K_7T+ X with K 7r+in K^atv^s r:52.5GeV 25 520 5 O ^. g 15 n \ 10 m ni 1^ 'if 0^ iii _L J_ 200 2.20 240 2.60 2.80 M ( p K"TT+) , GeV/c2 .1)1 BACK ( /"WC -MAGNETS Dl BACK' a BACK CEBENKOV COUMTEBS : SCINTILLATOR i i i i i • — 1 - 1 - 1 7 1 c) d) _ + t + a All A" (3irl UK Pir . K~pir' '+A°(3«) 50- B2.21-2.33GeV- BK~p7T~ 40- F \ 1.09 1.11 1.13 (GeV) > 11 bl OA°(3ir)+ 30- H A°I3TI)" 11 " Events/0.0 4 G \ 20 ' 1 v - ~L 10- n n ) ko - il n n JLJÉ^ 43-1 Ln./ . . .X 1.65 2.05 2.45 2.85 1.65 2.05 2.45 1.65 2.05 2.45 Invariant Mass (GeV) I 1 1 1 1 1 Tlr-^hMT j a I 2 3 i 5r p p - e K~TT+ pX at ys = 62.8 GeV 180- 160- 140- tfl 120- rv Hn ° 'V 20 2,3 2.6 2.9 M(pK-TT*) g I00h e 80- ^J1 60- i Mtf l 40- 20- JL _]_ _l_ 1.70 2.00 2.30 2.60 2.90 3.20 M (p K"TT+) , GeV/c2 KlG. 12 si S2 Intersection 6 MWPC ' s MWPC ' s !H m^^ri- 71 ; VETO 1 ^ COUNTERS Ji !lL-" \l i i( "•" " -• M 300 300 2.0 " " 2.5 3.0 Moss GeV/c2 il,., li •iOOO da 0*« l_ .ÉS«.VC*a j>+ 3 6eVMÀ ioa- D iS I ^e/n,S3GeVCl1,103 eft-, 53t6l6cV[13l •to. 3- 1000 • D'fuJ \ h • ' r (ft) V[1S] too \ - \ K"P« to i .5 •* 10 c 1 1 1 1 1 r c (ft) r DJ> IP'*' x«, K + 10 i> 0' 4> e/v p to V,P to' 10 s 1 i i i L. 10 10 30 HO SO 60 /J (3eV) 100. i r • i ! 1 - \— f\ , rA(ius) \ (M) 10. \ : . \ • v. Cirj ^\- •. \- [17,13J \; 0.1 I 1 1 L. - I 0. 0.1 O.H o.6 O.g 1.0 X Phnr-P "A-1 coMnbnrnljmi Pub. // TN HU/01 May 'Mi. I HUM _Nj.\vrpi'\!ii: 2.(1 ^ M -U»m COMMENTS ON A PRODUCTION AT THF. I.S.R. c .(-:. f.'i'i IIT i i Rjym riiiixiJ'TJii • The id'-a of the experiment, was to favour forward prod ti r I i on of cita i-riicfl p.w I IPICF, To (Jo ( li.i I we had a 1 r i y per on arm 2 wli i eh cons i s t IMI ol' a scplnm of small ape Hurt! selecting protons of more lhan I f> iii-V/ r., i , i*. o I as I i i- and nuns i -o 1 as t i v. pro Ions + a tail of nidi nary I' r a iviMMi I a t i on pro I on s , On I. hi1 « I JUT side Hie IT was n mu M i par t i r I e spec I r orne lor1. Tin' forward part. was a d i po I e used in 1 !>?:!,'"?•! by experiment IHÏ(i;i or wli i eh I shall la Ik later. II is i-nui pped v. i t h \'V.Tl"s and lias n inotntncu I urn precision of I . r>~, al HI (!eV 'o , II f'erenlov (counter's allow lo recognise protons and kaons JIIXJVP I , fi GeV/e. The solid nnyle lies essentially between 0 and tî« , To increase it. we have the so called l.SM (Lamp Sliadr Maynel) which is a loroida! ma,T ne I ri|ii i ppod wild d r i f I r h amber s in front and !>eh i n The triuWM" was thren particles in Ihn dipo 1 e and Hirer particles i ii I he l.SM, so wr go1 a ' least (> pa r I. i v I es in the final stale. This also hr i M(js Ihn mass of I. he rxc. i I ed syslcm a hove threshold H.I Lo produce the hc . The d i s t. r i bit t i ou of missing rua s si; s to t he pro I. on goes bc.vond i he d i T f rae I. i ve re g i on , wi I h a t\\\t\ s i I hr r sho I d at a bon I Id Phar-P ïU-1 eol Inborn( i TN HU 0 1 :io. iniMi 1 now show you the K_piT* and K~pîr" mass ft j s I ! j hu I i ons i F i ;>. Tliff is a s ha rp r>, 'A si audnrd drv i ;i t. i ou peak around Î'. ;ili HrV ; • lability In find sunli a peal? any wli.r rr is about IM- > . TI I ) • li.i'i' been publ i shed r' I t» î vn you now some morn details, f rum i; i bon i I in"; is. 11 Th^ evperimenta I muss resolution, lias n of about 1 A Mr\ ;i I he computed ^ is about (7 I'.cV so Ihrcr i ,v i(i/i|e /;ood a/:i n-iiirn t , Ki 11ml Uiboni deduces I ha I tin; nnss is 'Wûl ± U) McV inrludiiw.i I '.• v i rm -i I i r IMI'OIS. This is to bo compared «i lh I hi- SI.AT data i:::.'!i~ .')i*'' i i f . 'Vite fiiull ifil (ri l.l' of lr«i:);s a ssnr i ;i I IMI U i I II l h r KIIMI-II IUHIHM' than Ilia t a s soc i n t IMI with the ha rl ground . iii) Usui» lb- *a I h.wi , tin I. iv i I h more earn about no ruin I i ;-n Imn, r I f e r1 m ml s .. I , i," i !"wi i f i nds- a i:rf>ss-srnl ion of n bon l M j/b in I he ri'iiion 1 ()• '.' ;:H r;,. . ri -, • . M . ss-srrl i mis ( o t ho r expp.r r i\ t s and 1 heorv ) MKIHT linen I ltf;n:i:») iiKinl only t h e forward m.-ignrl and wa: cnlr in Hif high .v region 7f> •; x -' ,'.). Mi this rer.ion (In «•b'-'i j .".*: !jili.JiL!l A.- rrnss-srei ion (multiplied by ^ I" take ml» ai I'MI I, ^ideO is about H //bain, for I hi- K~pjj* channel. The SKM measured about. A /fbai'n1' Cor each of llirir two resonant eh a nne 1 s K * p and AT . Us i nfi the S I. At? bra neb i n G raI i os* > nor cm mill f i ply IIII'SP nntnbers by :"> or lï, getting something I i l< c :.'() //Knit |nr K-pi-. to be compared will) the fi fib of Rt!li:i in a smaller x n-fjion. 'I In si' I tto i e su I I s are poss i b I y no I i nr ompa I. i b I e , nor aie I h- : i.e. essar i t y iv i I li Hic a bon I M //b of JliiUli, in the r ange .ft - .!( 1->i \ i\ i and for the «1 i T T ra i* I i vi« region only. In view I won I (1 JJ h p 1 o make, a roinment. on Ibis cross- sec I i on . W . He i s I r> * romp i l ed 'K" ii •*'•«< :i [lal d.wdx law, limy find o about. :Win-iun //b (point No. I :: ai . i u I he same range, as cfAf) with the same 1 aw. These numbers are order of in.i (in i ( ml e wise in a freemen I with the g 1 non prod ur. I i on mode I of Krils.rh and SI r en i<,r- » , Note thai we huve just heard Trom Pr . Sens that "i pi-'diirlion is in n yrecnen t with gftmn exctiangc. Note a i so MI.-I t , doc to l he sina II x of the g I non . g I non exchange Y, i 1 I prod u re hi i;h- x e\ r i I cil AH syst niis-jiisl s i m j 1 a i I y I o poine r on- e \ c ha n e.i- ' I I d i ( I r a e I i on ) . I'l.ar-l' HA- I col l.ibor n I ion I'll II. il 'IT,' "". IM l.tnv Mil. I!ll!ll :M J'j.-;...|.ii£.l..i i:ji.ii:.ii.M.i'_fj_«jjjc.s o_C /v. Hill' il'1 sonn' pli1 I i III i ml IV results, ivliirh m i y In* >= «• rn i fur lo'i 11 unit IT s I ;,n |.I.ili.in -it xe°- .:,. lolloiii'.l by n ilrnp-olf linr.uil II i -X VII 1 IM'S. • ll-M'-nff is sliiipi-r Hum I In; I I - X I I ii w foiiml for ini-liisi p. . In,- I ion. This ni.'iv mini' fl'i'i» I h i' l> 1 ii s r s i I, I roil HITII In- n.n Ir h I'i :.') I'll i- I'.lK-na») il i si ri bill inns follow n I' -hi', (or In, I I IT mi -Ii'I'i ''I lnw wilh h ;i bo n I :{.-> (li'V-i. II,, Hi -\ nii-l I', il i si r i hill ions nir llir sunn' in I In- "il i f I i ,i i; I i ':<• " rri'ioii lv, : .11. .ilioul I'.ll':. ol I hi' pi-.il-- i or 111'low In - .11. n limit I "". of Hi,- pt-.ifi. Ailiinlly iT oui- plots I K i/;. 51 tin- IHIIHITI- N of i-i-nu in tin' sii'nnl bin vin-sus x; (\ of tin' ri-i-i'il protein) or t.'•: = sll-irl, l_\l.'.- n Kill i.-i'i-il our rin,Is th.,I lln< ,\'<;.|. ) .l.îj:In':iinr_i.T II K.I.. Ill boni I-I nl.. Phys. I.i-t I . ^Till MI1TIII i:i7. 'J i li llolllllnlil'l-, I.Ill,- tlll^ll. .Inn. l.'lllll. .1 1 IV I.oi-linnn n I nl.. I'hys. I.nl.t. holl (III7II). I I :l . luijniil I't nl.. I'liys. I.r I I. MjJ.ll fll>7!>>. -Ifia. 1 1 W tii'i s t . i:i:i!f. i-'i' ?ii-?n i in?!)). 1 1 II Fiil.sih n,i,| K.H. Slri-lui. 1'hys. I,,'I I . 7Jtll IIH.III. 117. ? 1 i; liusl nl son mill t:. Pi-I irsini, I'li.vs. I.r- I I . IS7J1 ( I !)', 7 1 . lit. Ccrenrf» CO copies) jpptjrr. mogne: DonDle Sepium Mognct LD'"D SHioo '•^g->e' Number of evenls / 20 MeV/cz o o o o o o o o 6 o "I " 1 ~1— 1 ' i 1 1 1 K a - CT \, •c r? " \_ "^^ : "~^ v^ V"- £ j. ' .— .^ ;*: i,^-' 1 , -' } i "a "O ( ( .- ' f =4 Jr,y 3 + 1 j 1 1 1 i i i i p TeV/c LAB .07 .2 .3 ,4 n 1—n— "Ï2Î 5000 2000 1000 FRITZSCH. 500 JO ^ 200 IQ 100 Q t 50 Q. Q. 20 10 5 2- .n , T —r x Distributions x2 > 0.8 • Signal bin 1000 6 Ucickgrour.ci norniolizod 800 600 -% 400 I 200 0 J I ! ! 1 ,, DO:— o _ Sji.cvcci tr;;;;;r U.U 0.7:0 O.'wj 0.' STRUCTURE OF PROTON - PROTON COLLISIONS WITH A CHARMED HADRON PRODUCED R.Sosnowskl Institute for Nuclear Research Vlartan Since the first diract observation of thu charnod particle production in hodronlc collisions [°1j (oee flg.l]. furthor expori.-.runlo [2,3,d] have confirmed two unexpected foaturoa of thio prococo t - the production crocu section of charged partlclos is of few hundred» uiciobarns which is largo when compared with theoretical predictions. - the differential cross soction decreases rathor slowly with the lncroasing longitudinal momentun, p.. The nost ecnplote information concornlng the strueturo of oventB with a charraed hndron produced le published by the CERN - Colic-;o de Franco - Heidelberg - Karlsruhe collaboration [l,~] (ceo flg.l. and fig.2).Tho cuts Introduesd there in ordor to enhancï the D* and A* oignais ollon us to establish the structure of these events. This is visualized in fig.l In which an event Is represented in the c.n. monentua space pL - px, where px It one of tho two transverse components of the nomentum vector. The structura of event* cloarly indicates that the production of D* cosons and Aj baryons le very peripheral. This statement le •upported by experiments dsdlcsted to chars search at pL « 0 In which rather low values of the cross section /or ite upper limit/ was obtDinjd [ 5] . Also the experiment which observe» directly the charmed D *nd A* partiel** suggest* that the differential cress Talk pr^sntod at tha workshop on "New Phononsna in the Fereward Olroction at Collider Energies" , College de Franca , Paris 28 - 30 September 1979. - 94 - section d5/dx la flat urban plotted versus x « pL/pr „ J 6]. In the present note we would like to call the attention \o the fact that both charned particles, j\* baryon and 0* meson, havo been found In events with the Identical structure. Tha experimental cuts imposed in order to enhance the D* production ere equally efficient for enhancing tha i\_ signal. This observcti: strongly suggests that the production rcochanlsms for the two kind.i of particles are also vary slollor. On the other hand the quark contents of both particles considered lo very different. The .A. boryon may contain two valence quarks of the incoming proton, wheroae none of tho quark:, in the 0* con be of this type. It is therefore hard to explain hhy D* aesons are produced peripherally vary much like A* do. The slnilarity of the production nechanlsm for O* and A* particles, in eplte of the difference in their quark contents, can be explained by assuming that 0 meoons are dscey products of a hoavy boryon, B. The production neehanlen of tho baryons A* and B can bo very similar as both of them nay contain two valonco quarksof an original proton. Although tho hypothesis that D+ •aeons are produced as decay product* of some baryonic state, a soons to be very probable, very little can be said on the naturo of thie state.At least three possibilities have to be considered at present. 1. B is a charm-zero etate and It decaye via B-D++N+5+ plons where N «tonde for a nucléon, a baryon can be produced dlffractlvely. 2. 8 is a heavy charmed baryon which decaye into D+ and a nucléon. B - D+ • N • plona 3. B la baryon carrying a beauty flavour with a weak decay according to B - 0 + N + pions/ lapton pair In all three caaas not only tha 0* • N pair but also the A* + pion •yoton is klnematlcally allowed. Because of that a part of observer A particles aay have tha origin ldantical to that of D* mesons. - 95 - Raferancoa 1 CERN - College de France - Heidelberg- Karlsruhe collaboration D.DriJard at ol., Phys. Lett. GIB/1979/250 2 K.L.Giboni et al., Phye.t-ett. 853/1973/437 3 W.Lockman et al., Phys.Lett. B5B/1979/443 4 CERN - College da France - Heidelberg - Krlsruhe collaboration, O.Drijard et al. Phys.Lett. 850/1979/452 5 W.Geist, "Production of charmed mesons and charmed baryons at the ISR", talk glvon at the SLAC sunmor Institute of Partiel.; Physics, Stanford, 1979. 6 E.Klugo, talk presented at X International Symposium of Multiparticle Dynamics, Goa 1979, W.Goiat, talk given at the present workshop. o co 2.0 3.0 4.0 M (K 7T7T) , GeV Fig. 1 - Distribution of tha invariant mass of (K ,J1+) eyatem producad In p - p nollialona solactad according to oritarla A,B,C, and 0 axplalnad In fig. 3. pp - p K_77-+ X with K-7r+in KKatv/s = 52.5 GsV : i (A)»(B)-(C)«iDWE) 25 *20 o -=15 n i £10 ^ [u E nJ IK "«I 5- '\f flf. 2.00 2.20 2.40 2.60 2.80 M( p K"ir+) , GeV/c2 Fig. 2 - Distribution of th« Invariant aaaa of K ,p+ system produced In ' p - p colllelona selected according to criteria idantlcal to those applied In fig. 1. (A) nch < \0 tPx (D)ZTp^>0.2 6e\/c (B)|::-xl>0.5 X<0 Fig. 3 - The structure of avonte aa determined by cuts A.B.C and D Introduced in order to enhance the D* and A* c signals. J STUDY OF THE FORWARD PRODUCTION OF HTGH-MASS SYSTEMS AT THE I.S.R. A. DIAMANT-BERCER I PHYSICS MOTIVATION : Results of R 603 II PRESENTATION OF R 608 III POSSIBLE EXTENSIONS OF THE PHYSICS PROGRAMM. U1 BACK .MWPC M»GNETS 01 BACK 02 BACK M -. SCIMTIU.MOR -> 1 1 1 1 1 i r o FER/.ILflS j l*»Pt«9 d02-, iû>, 2C0M/J; 1-a Pima V P- OH r PP-A'^X li , 1 \-> Ad- Ik * r • • ' 1 • ' 11 * r- ^-ft-hV 0 il/iiCrt 1 a?- ___ J" .' H h 1! i ° t»ir iranw^r-»: m.-nH-iiniin (1.6 < /", •:." 1.1 GeV/c. Id- it I I i' 0 t Hfc |\ C.!.— I— 0.03- I A° Fig. 4. ("inal poljrtijiion valui-i fw ^fi. ifi and .11.'? I r.?V dais «mpkt si 3 fua;Mon of l*t. Thf! ;*-ii if fï.nion i • ' i^ 1 1 ' 1 O.f 0.» 0.3 1C fllVSICS LITTERS n ^à igco u I *—-.. ] Ï [13851* w- J*S r « m BO ao MiA°irlMeV w HI >,' • • • »> AW »- ••'A r^x -ij^ir ,• ui» wo IIJO M[p»*)Mrtr MtpT"|M«V Fip. I. (nvatbnt ironsfwclraof nateistudiedia)p»~for Zveitcx^ *5 cm; lb) An* for topology shown atimcn.Z > IS cmfot Am" joint vertex and £,\ > Z-g * 20 cm: tc> ,\ir* and A»" foi lopolopy iho»n, \Z\ < 40 cm foi An* joinl vertex and Zq\ > ^primary • 20 cm: (d) p** for/verte* > 20tm;(er p»*foi fom-track topalogy ihawn,when>|.|d6 <.tfp#-< I.I!6CeV: shaded area o ^if»—*~i when 1.08ft <,l/p„-< l.lOftnr l.l?« <,lfpn-< 1.1-16GeV;tf)p"" for four-track topology when other p*~satiiflct ). ! 0$ < ,Vp„- < 1.126. Lxh t*tm il ptellcd only once. Vol,,» SSII. .ii»Mboi4 —i 1 1 1 r- [2 7.IS [>. I. fa) OiiKibuiion in longiiiuliiu) i Ccynonnl-jr ht alt identified K~**p evenii fe*ent« tcaled down by 1/5 Tor dnolay purpcicO. ihj.l-J nf ihinc oont» in the m*jmni mawnnçs J.25-Ï-J3 GcV: |hl contoun ol" i)DlruOn:-il«ay acccoijn^c 'J K"s' n ^ii.-nt in wc pljns gi itt in» u uni masi-Ion^iiudinal mom-.ntum. Viluei ihown ate tntiwwt wciVMHt: uUo valid lui (C'a' p lytUmti- DAIIA'P»)* ?:U1.0» l.ii x(.13 iGm O A'tM Jin, A ILJ1 1.65 ^_JfO2.C5 3.45 k2.0 5 i es im 2.4i Î.04 7.4S r«. s. ut A*> H i'-cinin (|al::.|i:iili!il:irti iliou will) A Bettf* «'<*t«J>A'e R gog ggfet^gfe; ÇgRKT LOS ft*JGS(.«rS SrtCLfl1/ ï. ell*J+- T. ftWK ft. SwiHu p. sud,» 3.P 6«rd IÎR ^l'uitiin R. HaddocK f). &.rj. T. Ha li* 3.i. a«,s •I. lArbi'w A»f. SiamovJ', <îs M. IsclemaH J. <>i»h.«h>ri« M. 1f»U*»it A. fte«rJ A. Rett P. ftoi/i'.jr^ P. SeMein J. ZlttMb'.ry 2w*ïî v • •<^3> 1 —' / • «^ 1 ^^~~^-~'l [ i' 6^; 0.3 UM, 10 U /* '4 " u i rcv/c) 25 Invariant Mass Calculated feoaetrical acceptance» for lndica'.M Jtttes for Jl/31 Gev 1SR energies In proposed spectroweter. Dashed lines are snte acceptances in RÛ03. CoMPftRISOHf w.'tf R€o3 flttep'ai.te R<<^ RCo2 TDENTlflCftT'QiJ des PftftTlCULFS OpeWu» oujtc (Ml.ii Sî. 10 IJO.IÇO Hîv*W*M* âLulCg . IT If Hh«*eK't Rrrrt (T»M ».!|7 0.1 leuaH »-) •?.« i.r o Ja«e (T,w) I.* 0.Î RtS«uJV*| — Uo*. «m (*) o.î IS" TT 0 0 K K K»fK>(c S»fttw.j «T<) o.o',-o.'| 0.0M p p p © ÔP/f TA) «-'if 0IÎ & 0 1 © K P ® TT 4 1 E ® © K MtMxSe-i cl ucP> « •2« ie 1 • i i i r.u &!/'«. z.r.eo w/t o î io ir •» *r a î. IT £.i//t 2 ( MU) ir.'-r &*'-. Î.I7,J».I,OGC*//C. SoHHARf of me PWflcs Pieos^<4 TlMF TA RLE" .Jutlutive eocu,»» . fa^ial>^ di"ifvi bu ton o^ Hfss t/*J*s •piffiaA.,u t eoawfs _ BI Pfiufe'ct uj>" £~ P-» Vyli V totwU f>-P e©!!l'*l»v>s HIGH ENERGY PARTICLE INTERACTIONS FROM 10 - 1,000 TeV: COSMIC RAY DATA AND PROTON - (ANTI) PROTON COLLIDERS* David B. Cline Fermilab, Batavia, Illinois and University of Wisconsin, Madison, Wisconsin A rumraary of the present status of the high energy particle inter actions iron reports to the Kyoto Cosmic Ray Conference is given. An attempt is made to provide an understanding of the cosmic ray observations within the context of observations made at accelera tors. In particular energetic charm production in the fragnentation region and high p. jet production could account for several unex- pla ined effects. Lmphasis is placed on the implications of these data for the next generation of storage rings (pp at CERN and Fermilab, Isabelle at BNL) and the experimental detectors. A brief discussion of possible new effects such as delayed events, Centauro and deep mine experimental observations is given. * Rapporteur talk given at the Kyoto Cosmic Ray Conference, August, 1979. Text reprinted from the proceedings of the Conference with kind permission of the editor. L Lll *1'£±}.Z^JS™. l« rtf tntrr •it» to no ami l-K 'C> " 1 *,.crime i ts lie start this talk with a short review of the "status 3.5 Prompt u Production in the Atmosphere i.d Lone Flying Component _i.7 Conclusion New rffocts l.l Delayed l.vcnts J ,3 Ccntauro livcnts •i.l l.vents in ilecp Mine l.Kperimcnt» 0 2/3 -1/3 -1/3 1.4 Conclusion Mass -few Mov- ..'& •vS.5 C«V (h'cak l'rospitl<: for New Madron Colliders TMntitioi. u - d (t * h> b « t 5.1 I'rotort-Antiproton Colliders (J'J Uound Not t i.i 1-M'ecieJ C.rowth in I'.nergy and turn*nos Observed S.3 Study uf Ultrahigh Inersy Interaction Prospect* for the future (v ) 1.8 CcV «.A CcV L •t exanple ihr- wc:it transition .'.•»!• iiHi.lK s1.ltti'Hn)...-»r.iii.nit- it wrv 1 u j;r • „-i.r> tweeii ,1 :inj charm quarks ha .s heen -ifiJied in ni-iitr f. ;t... r-i tic '-•' -••.('l.iii.cJ l.t r»i*nt]it tu- «>th vu. i : -i *.(MII i. \* .»• «-V-IMJ-IV ..Mi-iaci i.u-.h nu-1,1.- ut with llie i;|M notlcl. S«iai«iii»y perhaps lin- reactî , . .11 ir. • ., ,tit i r v i i ! 1'i^li n.-.i in 1 u;un> 1.1. Such itH-ini,: ^ xp.-ï ii-i«-.« p.^i-lv i "i.i',.1 ili.iv" nt vhu-li mm- .•: tin- I'p.jtir,! i-t.'|'t-t I i'-1- ,.,t Ihv i .11 ton!- l.mt ijiiiilnicil iin 1-,- ,l-.,i.,.i. |..t ..,.-rlc ML: i:i],n'.< spii'. 1/: partons I'T (i.itî. J i i,,i i |.» i] 1 M-i.viitii;; tlepnWrmi- (;m t'V in nstirr.l as in-n m 1, m, 1.:. <:iu(M*. irr p-irton» of -pi" '. though I" -.ii.I- tin- •.Mfii»: ivf.-r-n.li»!. of s iu 1/: p;iitoii*. It.e i.uhi r t. .m ;il<>. Le oh* tt-ii "1 iln-.ii- -r. ••-. ri-<' to "sv:>l nit ni'l.H UMI?", which u'i- '"''' m r.f.nruii' «c.-i 11 rring exper irn-nl « tlwoiigl, .i-.-t". i:i t :i i ii to deduce the fract IIMI.-I I nouent un dcpi n.li-nce ni f ni, fiii.il states ;ic ^hiiwii in ligure l.|.' I'it- ;-l;i'ii,s- our ,'tnpU- is Shown ill ïif;iirr 1 . ?. These i.lence for this privons in existing tnim tf*nll= .i,i- in ,M.O,I ;,ircr:-i-iit i, i I h t l.r iin.int "'•. lilimnmly ii:mi c *• l:.i->i I'-'IM in hhuh Hu- sl"«'« raJiiIint. it c alcn Lit ed. I !.«• '•inil.ir information about «narks :iml (Mnens ha- Leei, M.-iHrnia v. ntvin^ "Lil-nmtorv- c .in provide :nld M ion.il n.for- ol-l ,I med f f tira e*c" ami c\ MM t t er i ng c.\p''i inent s . There IS • it inn ilu-ut tlu- -pin 1/: pirtons. renarkahlc agrecwenl between the n-sulu of these v*per incnl s. liadron-hadron interactions also show evidence foi part ont ami «liions, J1 though present accelerator energies .-ire i on low to provide tonpletely conetncinfi evidence. A striking eonfor- »:iti0ii ul these exjiei-tat ions tomt* ' fora the pro.lintion .if iMj • it liiph transverse nonentum. T[ic scjctvring nroff»* 105 l g iv»LEKt QuiOKS .. • u - u • if* " * "' ' ^ y ; t.l,<...=l.l| is pxpectud to give a 1/p^ depeiulence to the cross section for >\ ^ w the exchange of spin 1 part teles UluonsJ.7 Such a dependence ..as hecn observed recently at the 1SU (TiKiire 1 .1 ) .ft lliesc i 07b results are in good agreement with the QiriJ calculations. S 060 B 0 45 S n v> o '^>r*[IM' (*0«*H|iINat** .—'N»H*IMWr; (TNl npl f, 0 15 V =--^=- y ?( •»- u0 3^iâ*0 20 0<0 0 60 y0 8 0 ««•((^l,lt' l .-_-*-_J__i_—•-. oo au oio ois ox ui.l ..! m l"i*% |cs "f These bosons vith the best present nensu n-(it* uf the Srinhi-rp angle are \. » II r.eV X». «fi Cet Note that the I." rross section r IO create than ID n nn hirne ,n ultrahigh enerpy. This s tct D7Î i? perhaps !.i fi emmch to pioduce sou 11 effects I h ene Ry air «hou'er r csanpu- Figure 1.5 «hows recent results on i\! production Ihe next generation of haJTon colliders have been designed <^-r,n-.f a. .he Sermiab I.rpton rhoton Conferee. I* ArP;.rc-nt- tu have adequate encrgv anil luminosity to observe these bosons, Mien- ,s a large cross section for A* production in the if tiny exist. {Section S.3 1. i Charm Production and He-cay Some estimates of charm particle lifetimes have hecn • t.Uned it, neutrino experiments kith emulsions and MK Hie earliest clear observations of hare charm stales came from neutrino reactions anil c*e* collisions. Some early cv i • dente s*ay have crime from the S pmticlcs observed by Hits and his -13 collaborators.1- Recently évidente for charm production in . 7 x li hadror. interactions has accumulated. There are three princi ple 1. Production of prompt neutrinos and muons in 1-7 * 10"'J sec hears ilimp cxper incrtt s1 * i. 1'irecl observation o{ chain hnryon production lm.Uii.ive Pn iA.j in pp collision-: in the f ranmentat ion »ej;in« at the iSR' * The iiuh.sHt- production of p;irt ivies in pp colli sir. '-en studied exicn-ovely it ietmilal. and the 1SH. lh *. i'ire-ct observation ef charm events fron pp idente thai le '«( " •irrri collisions in collisions. lS iti- i-v .,re w.tcrvsteJ in the i- ultr:iluKh energies, even s ma H non scaling efl'iv niant. Two sec of contributions to this confer i.!.he-=-:ed this ivSHf. h at there :irv .ij-.preei.iMe -|.n* 1-tffi.ii, M»r as „h»uii IN I ipire- ! .(• is: to Simple Seal in; SU to Male Ure.U.nv;).1 :.' '<*>' "- u"s (b) ,• i -t .,! . , i h< •- . ! ;.,i.--ii«: » î il"' * • r it, 1 . - /• , o-^* .,,.... /'..L.r, { i?.. 1U-. t.ii. 1}' . \\\ I )I?M": 1 . ,1,,--, l'-U »J 0/ M o-j «H oc c-; .": !J oi .' . r.;],,-.,',, , t .il . . fl»v.. 1 , I .ti . . i '.. . Î- St *!;,(>. f, * ]\i-m;^ i-i i - . i- .!.) . ;•-.'.;'.'; ti.. ••) ' is. In' 1 i-i-.i l il- I Uvir M ri. .,..„ i • :i : r.'.\ . '-.-v I.IIM . nil ;i i t- l'-:' C, tiV 1 L \ •• I 1 (•li.ii tf.l .. .i . i'uli, 1* : !* ,t . n. Î;, i i" -u..i î sy * lliy. iT"-.' 1 , II" (1 '"'U Mte i.tu^f .! iM • p.-.h^.tioiK fo 1 i..;n- . . 1 . L Allot lici | v could <,-( gt-sieJ MJm.. time ;1(;o that could fiivr Mftt' l" a «iif •" 10'3 «v as slio*«> in |:jgî 2 • ' iliJJUîxJîcattaring, llu- pnilon-Kluun-QCB node] outlined in Section 1 hns hcen applied IO ihc piftduction nf bï-gh ri jcîs aï very high energy- lliv inUtiMivç jet crass sect Uni ,v sWj in FiBure :. 1 Tor n-n ctUTRics I |.A)] - 2 \ 10'5 fv nnd : x lit''1 ov.-* At very li< ph p. (p^ > 2011 Ci'VVcJ the px dcpendviue UUs like ^ p/, its exPctied Change fo lion, tl inclue ORS section fur j» i>L>D I Tims. Ujs ffinilfl is is ' prndlM t ion should be r; prati.ihlc at thl: Tor pj_ > Z CeV/c i al. Pi, *" S tnb ; of the .il i '"S1' Pi, production as suggested prev imisly . * llowcve i am ion must he applied to this Litter conclusion si: a very model dependent application at th« <)Cll model. ==-}«=* vif. :.i ..pprir, Ih.it i),t- nil fl> .il T'"^ iilinj: ITCI 1.1-1 n. 1. h.itn pi ha fa c«tukt . s« îîsvri i.iï •Jti-i! IP ,7Uini'll' Il IRtl lui '•••'!, ffl.'.l,-!- pu- tl j.rmlm I . ! nh ..t vt't» |tlt:li ftii-t i;v. : h<- ...tVl lviV^-H* >.'lt> l-IVi- .111 o-r«•-•.!' *•--••*? t.. A.'.iIJi ft :.!.. I'irvs. U'C t . tidP, "."fT ( J'IT? j . ;>. U,ru-, I. 11-iUcn and J. I.Jthi-"," l'hvf. lie*. I et t . U, Ji.l». lu'lil, V..C li>x, ,inj S. I.i.l fr.vi, pTiv.itc minium u ;il ion. J . Li>n«l Atwt -1 - «hitMiXw, Sutl. I'IIK.. î»l^. >M Il'i.'"i; .4:^, Y/ 'K ( 1,.,11-hi.i» .itid M. H-iv.-f-M. "rl-Unki É'rrprJdt !!!< -11 r - Tfi.jo !l"*si. t!.[\ rcyia'.art, I"KH. of th.- hotkslu*p «« Vrolut i»p li,,.K I..MML-.I,' Hipl- l.n.TKy rtPiuîi-lm.pr.toi. i \,l 1 « - ln..s, iîfïl'-ict- i Man it, iO'S); ï, liaîren »tni t'.':. St.iti, Ki*i c JET x 'Jf. •.I:C BANL-E Rc~qe c' f- t ."> -02 Tev > S\a, ~ 20* PTrm ,-25 GeV -• ' ., R-,-, n c Jl KOI 9 ' ot> fsEy/TE, (cosmic r3y)% Z=2PrV,/7(ac«!eio:ûr)'* EyîOSTeV^^-ZïOgÇ et ? T.'V foi A lot ?-t TrV f r>r >\ h'l i.: 1:'! : .tel M. '•.! ,'iv.". :lv n-liv.iiit f-ir.riftcrs ttl tin- ttirec f.vjn-(i M-. ..nl, • i-,-t. ..-I' »n the emits tli.it .ur t>ti'Jiiv c.L HI J l'-l.. I-ir I il.ll I'lH-lfV OU nn thC IllKlînnj! .1 ||J the ,ltlj;nl.l >> .-i>l <>l tin- Jet'-i t.ir lvl.1 l>i V ini':.:it it ! in ] Cil um ih. ,,-M..f ..I -I.-K* which arc MIC riri'J in I i^urc \.\ i tiir "K. .liit.iH-iyi fxfi-r ir.i-nt .^ Note th.it tlu-sf <>icpi*ti- ^r tli. h. h.n int -T the 1 ru lu'.. i-.r .r-.l h.r 1<-»« lines .it hi.-.'h :i 11 , rudes . * Ivi.l ami i-O'tJ'.iri'J with «indel .nknl.,1 ions.'' ...it., ki-n ti|'nrli'J on both oT these teclift-«•;<••* . '•'illi .• .1.11,1, (In- vent i il question v.is posed : i « then* iiitr «vi.it'ti.c fer iarpe JevUtioix fr.-m «.«..TÉ inf.. '•*• Ht. Pamir group has compared the expects- .nt (..in . '. is self explanatory). i. t 01'**-•* i«<*tt of "» "b;tpc of the JistT ii*>'t i&n ticar conclusion is ih.it the data .in- iticnn- u[ 1 = l/rij with experut ions based on the int with .i pure* scaling noJel where the I cross section does ntu increase. Hitce .in «.-iliiii; ncdel (FiRurc 3.4). There i = nu R ttoss te. iat low trois scaling oa thi-, UTSStircments of the "phoîen" density •apidiiy, and comparison with acceler itnr data .tppe.tr to show a considerable increas : at 10 - ion ..«. .,., atory < crjjy {Figure J-M- <:r i. Cil dilations based on a ., expected piuon spcrtrura a "-;-• in deep mine exper ii.ionts arc Riven in Figure 3.7 flWl .1 sin! compared with the data.* There is pnnd agreement iT-T Ji •-" [^ k •s 71'^--, b' € t :atc j< (r»»l«l 5«' V " «**= (pr** -*-*> •? ^ WO*** 3 . 9*60* L v I 2 5 10 E^.TW 1 J 5 E^T.V Uuos «em col apectr* Dorp UBdrrerouniJ «uon at a«o i«,»l. pairs -tit» in «hKccter. L et inn !<> tin-' At itu*. mcoi ni(; th-.' ii- ( • in r;cv/i t and the |U. sneitrum for the (* .let • s a ."lear deviat ion fro i an exponential hchavior n rrv U«- pi [see Figure i.~\. The Ml. Chmaltat-a j: ' " alcujati <-x|.fii- cones frnm the measnremci of the f.|»J.> i'T i families at verv hich enerçv. Tip. 5.3 shows 3 the ' |U-i ilisirihut ion fron one experinent. ' - The rate for ! ." 1 irt events with hif;h pi iv l.'t-lf):. .mil is consistant s. wilh the expectations of 'Up i ,i Ui.la t ions,. ! •' Several spectacular event One smh event is called Car-to i'iT--e moncntiin of the two jets i •; 25 iieV/f. It appears possi- Mi- that this rvent is an en.-inplc of i pnrton scattrrIm* pro- c>' alihuuuh other ctplaiKit i nn< are rertainlv pussiblc. ta' X (."•ill* hi tli more ccmpl icatc.l 11 rue t lire sucéestive of «evoral i-i.li.it urn. Realistic <,H'l» ci K ulrir inns anil pred ict luus that im.lii.lc ilctei'tcir accei'tance .iml resolution are urpcntlv neciled 1 2 for the: •xpe nts. .1 rrn,lu..t i nfir?rj.iflr. a' 1 1 i 0 t.0 SO 3.0 Ihi'i-e i" now t-Diivinciin; i-v i.leri.-e that the X particles, st ohsr-ivi-,1 in p.t-1, are lil-i-lv example* oT charm partic • lue turn am) dee.i»-.lfi Volitional in fern» t ion about * par in- was reporte.! at this . nnfer.-mT. ' ~ It appeals that M- .ire two "lift-Times" d»r these panicles - 1(1 ^ sci :i H ' ' s,-, . Ihr pni.lin-t inn c res-- i.-rtimi at " I" TeV is in.ited lit he j-if.iti-r than Sell i.h. lln-se ii-siills art- nni ..nsi-ieiu h-itti the emeri:i"K «lata on charm prirtitli-s oM a ! Ï-1 turc '.'-I - . of tlicsc data i. The product toit cro*< section is in fuH'Sf of i mh, again in agreement vii\\ the charm pair production estimates at very hiKII energy energy (sec Figure Z.4). A likely explanation is that production in the fragmentât*! the I5N (see Figure I.61. S-5 Prompt n PrsiJuctionin the Atmosphere Several experiments reported at this meeting indicate th; pratipt wuon production mayn have been observed in the flux of atmospheric produced muons. Table j.i gives a list of these results as well as previous measurements at accelerator*, figure 3.15 shows these data conpared with the theoretical production of charra production discussed in Section 2.3. J*tic data arc not inconsistent vith large i" ections above IDt» - 1000 TeV ncident energies.13 TABLE 3.2 easureaents a Accelerators a.. d Cosmic Rays Source from Conference * primary* Reports -SO fioV tOO f.e¥ FHM/CFMH Data -v.5-10 GcV >100 GeV U*H" Production Neutrinos by Neutrinos (Referenc S-10 TcV > 50 TeV UN 1-11 M. WonDva et al . frw TcV £ Ï0 TcV MM 2.2-2Z Analysis of djta from H. Thorason et al. feu TeV £ 10 TeV Y. Mum ko et al . UN Z.2-^3 S.7 lont-liisi.tn l.irqe pt p n»Juefion o-(t« se, *l't\ red in [In '."!' nclPl, Rivo rUc to effect- vi to oh^erv.it inn- Mt the VO^M- rav nprrimfnii fnr li>i-n T.-V the ..ml I'nllnx rroin Ilii I-: In i proiltit-t i the ..erir-i.t.it îmi fee inn prftdm „- ,. .„. .K. '.- . T,-ir«r-l fitrf iiJf- tî'-ti r.ni rr.-ivcï di inm:ev •» T • ncter-: : Pin ld-iri 1,-V in.i.k-nt .-nere.ie-.. 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"J >'E> ),,,..., ,,„,, -• n-l Une e*|M 1 inentv tmil-l li.-ivv in principle nl-verved -.nth events, •M. «•lu.Mli.nM, -:t. luii :iud Ml. IMIÎ'II.' TaMe t.: lists t hr , ,1 !,il...t '-1. il.ii- event, ».-r.- »|.-crw-l. v. rv liV-lv -,u,l, ii-U-i.inl «M. il< -.•«•;; for the '.ient.mro search in these ciprr ilirnt s. t ,h<- ...-li-tt.-r, 1er i.liuh M»r>- ,.'ii.-i-i i,m> for :.nh tin- "definition" of i>„iaijro piwn .ilxive there -ire tun rMi-iil'- oh-erved at ;it. Ch-iCiiltav.i Lut neuf se l:ir in l lie olher <•.vn.Ti-.vnlr.. 1 lie re is JIO( ;, y|,.1f[> L on! rad ici ion here Nil it is l'iipoiliint li; note that the *lt . l'.i'iir experiment has «h'.crve.! I. Iiinh nuHjpli.itv o-f IL.IOI.IIIS. .ilmiit twice as many liipli cnergc events .nul won 1 il have exiueled 0 ; :-.:ill uuKil.oi «f * lr.r , l . lo see _> i '"t'iil.niro events hy now. \. U'n îiit'i eneij;;- '" 1I»"H-2("10 ToV incident energy). • r.-rrtuf-î ne li-tf.l in l.il.lr J.l. Ht. luji t>5 m'Vr -—1—.—,—.—!—- 90 m'yr Complote Kcati -. •*'..'' ' ' ,* - . « •*.S« * s •V-V: ^'' \ mime carlo analvMs j.f air showeT MMIU VIS reported. a> Iliph eticrpi' events were simulât cil in atmosphere interactions above the Jclcrior, and 1 he results of this analv.ii are ehown in I icure l.^.'r Note that no events like the two i:entaiun mho or MiDRo>( s it.jiof» events that survive the above criterion are observed. However one uf the original events ,* re|M cuhn e«l hv this analvsi*. Thi a:ialvsi> actuallv strengthens the arguments for the iiniisimi ti.-ii lire of the Centauro events. Nevertheless the other experi ment; have -n fai failed to confirm rhe fentaiiro events even thnui'.h in priiu-iple several -.Iioiilil have been unserved hv now. c.l in S ' i-.-M i It.rU--- ^p.iMr "I ('-..!;((•(• ((....t.,. ir lîiato th.il ...iul.1 .illi>i, a MMUII f»i Du- lut-' • will :m.l tlic Ji'l.'ftoi. \ te'- !»•»! 1- .i (•••mil.il îtv tli.it rli,- m, 1 uni 11 ' s.-! 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Vci'Inr Ko-nu i-r.irn.-.". t'rcti-i'JiiiKs of tin- Into "rial Nvmrino l'on fi-n-net, Vivhon, JiTf,, ||, | | ;1 s H. Reitliler. ami I'. :tTw.T-, editors p. l>83. s =11 proposal r-4'.' li. ('line. ]•. \1trlntvre, F. Mill:, ami C. Ilubhia, "CM 1 ef t inc Antiproton* in rho Fern il ah RonMi'r anil I'Prv IHjili pp C(illi. V JX^irn of « Froinn-AnTiprofon CulliJiitc Hear* F.tcrlirv CMN/PS/AA 7S-S. *• «. m. . • t prirent l hi- i'ii lv informât i.::i .il-uul hail: on i >. inter.i. iilinonf thr I.IU. Kurkshop on High .M tien ilxvit liailrmiit ml IT:IC t inn? in the 1 r»l>or.-itcrv •itv pp stor ige Rings, I'. Cole edit "f inn i,V tn :n(l[i lev. Die i.V.c nf ci/cnl-- «ill bi [197H1. rr Hi.MI T- > in'/'-.i-i. U The hijihr-H cm iti rlJ Id r,..l. HutlkcT, Atomic Cncr^y 22. M(. (1'K."' S. Van iler Mee r, CHIN ISU-1'S/7: - 3 I . Aiit'.u-i A Cm I'ln.'il Oct- fo lliuh lui it y proti at le lah. B. Pr< JulV 1 Î1TQ . lishi-.ll. L .....irU I. |:- l,i,.l. IU t>. .|»n i:<-V i' .;isilv «l-s • u^h r.iitirlicity m,l! jl a:.",!;'i'-' - 129 - COSMIC RAYS AND NEW ACCELERATOR EXPERIMENTS Y. Muraki ' Institute for Cosmic Ray Research, Univ. of Tokyo, Tanashi, Tokyo 1. Total charmed meson production cross-section Throughout the long history of particle physics, several particles have been found by cosmic ray experiments. Charmed particles were discovered by cosmic ray experiments before the discovery of the j/ty particles . In fig. 1, the charmed meson pair production cross-section has been presented together with the data of other particles such 2) as p'fK* and beauty meson(B) . ISR point of Fig. 1, is not _3 ' for a (DD) but for a(A D) . a(DD) increases rapidly from the 4) present accelerator region and it becomes 1 ^2 mb at 10 TeV On comparison with K* and p1, the charmed meson total production cross-section rises rapidly with the incident energy (E ). The 3 2 5) well known law a«(l/M )F(s/M ) only works over a limited energy and mass region. One of the reasons, the above empirical law breaks down, is because of the increase in the probability of gluon-p - _on, gluon-gluon and gluon-sea parton collisions with increasing energy. The precise observation of o(D,D) at the CERN pp collider is one of the very interesting piece of information which will help to elucidate hadron dynamics. 2. High P- physics from the Drell-Yan mechanism In the limited range of mass and energy of present day accelerators, heavy vector boson production cross-section - 1 - *) Visitor at CERN can be expressed by the naive Drell-Yan type formula .:*U/M3)F(s/M2>. A comparison between the well-studied Drell-Yan mechanise can be written using the Drell-Yan cross section as follows: 2 do/a(H/2)L0 = c (aa/dPT)|y=0 observed cross-section, dc/dP_, being K P_ at high P_ for cosmic ray energies (E-* 150 TeV)(Fig. 2). The asymptotic behaviour of da/dP-,, predicted by the above relation, as /?-> obeys ? law. A good test for the presence of gluons may be done at the by pp collisions (dc /t3P J — ) with (d-T/dPTl ) . The ratio d.T/dP,„i? p-p / da/dP,T! pp will be 1.2, 2.2 and 3.1, at *>T = 6.2, 9.4 and 12.5 GeV/c respectively in case gluons are not exchanged, i.'hen the gluon exchange process exsists, the ratio will be almost for all P . Thus the study of colliders is very interesting. 3. Centauro events The famous Centauro events are shown in Fig. 3. Two hadron rich events(a,b) have been detected by the Chacaltaya emulsion chamber group. One event (a) is extremely interesting A Japanese emulsion chamber group is now searching for such 2 phenomena by using a thick and wide chamber(% 100 m ) on the top of Mt. Fuji(3776m). First results will be presented at the end of August 1980. Centauro and other cosmic ray phenomena are nicely reviewed in Refs. 8 and 9. 4. Breakdown of Feynman scaling Cosmic ray studies brings not only information about particle physics, but also astrophysics. CERN pp experimental results will also be deeply related to the astrophysics. Cosmic ray flux measurement indicates that the difference between Y-ray flux and primary flux is due to either a breakdown of Feynman scaling or a change in the chemical composition of primary cosmic rays. The y-ray flux dN,/dE,, at E =0.1-100 _Y ID TeV has been observed as E dE and Y= 2.9±0.1 , while primary Y Y hadron flux is expressee d bJy EIr, y dEIr. y and y.lr y - 2.6 ±0.1 at E- =0.5 - 1000 TeV. The primary cosmic ray flux is a mixture of protons, helium, iron and other heavy nuclei. The difference in the power indexes 2.6 and 2.9, is greater than the statistical If CERN pp experiments confirm the validity of the Feynman will be attributed to the change of chemical composition of primary cosmic rays at E. = 100 - 1000 TeV or the change of power index of primary particles at this energy region - 132 - As shown in Fig. 4, X = 0.05 - 0.9 range corresponds to -4 -2 between 6x10 and 1x10 radians. Special techniques are necessary,for example, putting the drift chamber inside the Roman pots or an emulsion chamber inside the beam pipe for y-ray detection. However in the latter case the background from secondary beam-wall collisions should be taken into account. 5. Muon pencil beam Almost 18 years ago the big cloud chamber located at Wt. Norikura Cosmic Ray Laboratory (2770m)captured the very beautiful event of the muon pencil beam (Fig. 5). 5 muons passed parallel through the 21 layers of 1 cm thick l»ad plates. They bunched within a 10 cm diameter. The average number of 2 "normal muons" in this zone is only 3 muons per m . The 'parallelness' indicates that each muon energy was higher than 50 GeV. The dimension of the cloud chamber was 200x130x65 en . Why this event is strange? Can the event be caused by the simple fluctuation of normal muons ? Since the average density 2 of the muon in the area is 3 muons/m , the probability that five muons fall down within an area BO CF. is only 4.5xl0~ , which is negligibly small. Are they the simple decay products from pions or kaons ? The decay length of pions and kaons increases with the incident momentum. The 10 cm restriction indicates a strong limitation for the transverse momentum of the produced hadrons. The production height H of a 50 GeV muon with PT* 200 MeV is 12.5 m. H of a 100 GeV muon is 25 m. - 133 - Thus as the muon momentum increases, the production height increases. Due to the increase of pion life time with its energy, only the decay with P a few MeV will be possible(Fig.6). In other words it is impossible to make 5 muons from "T/K decay with normal P ( =200 MeV). At present, we do not yet have a concreate knowledge of hadron production with such a low P corresponding to an electromagnetic interaction (magnetic monopole), so we must introduce another concept such as direct production of muons as opposed to normal hadron àecay. The data was found almost 18 years ago, when short-lived particles such as charmed mesons or beauty mesons had not been discovered. The interpretation for this event was given up for a long time- I think that a new interpretation for this interesting event will be given by a cascade decay of Beauty meson (BB)pairs. The cross-section is not so low and so ;-.he search for muon bundles at the pp collider is very important. We can observe two, three and four muon events with much higher rate at the pp collider in comparison with five muon events. The total beauty pair production cross-section at E0= 150 TeV is approximately 500 ub. The curve of a(BB) of Fig. 1 is obtained by the CERN Goliath data point allowing for the increase in gluon-gluon and gluon-quark/antiquark collision probability. The 2,3/4 muons cross-section from BB is 10.6, 2.6 and 0.13 yb respectively. Here we have assumed branching ratio for B -^charmed meson is 65% and B to p 15%. a (pp •+ BBX) - 134 - at 20 TeV is assumed to be 200ub. Thus for every 25Q events at 20 TeV, we will find one (B,B) event. The five nuion observation obtained from a long run of 10,000 events could have been a BS decay. The search for the muon events by pp collider is extremely important. ( The significance, search for muon bundle/has been stressed by C. Rubbia in this conference.) 6. Summary {1} The cross-section of a(D,D) increases with energy. The heavy vector boson production cross-section deviates from 3 2 the naive law 1/M F(s/M ) at very high energy, (2) Comparison with da/dP_|. , and Drell-Yan cross-section da/{dM/2)|d at very high energy will provide evidence about the existence of the colour quantum number. (3) Centauro will soon be checked by a cosmic-ray experiment. The detail dynamics of such a hadron rich event will be extensively studied at pp colliders. (4) The investigation of the Feynman scaling at the pp collider for hadrons brings a very important knowledge on astrophysics, (5) The 2y, 3u, 4u and multi muon bundle at the pp colliders is extremely interesting. A cosmic ray muon bundle event suggests the successive decay of a BB pair. The total cross-section for (B,B) is estimated as 500ub at 150 TeV. - 135 - References 1)K. Niu, E. Mikumo and Y. Maeda, Progr. Theor. Phys. £6,1644(1971). H. Sugimoto, Y. Sato and T. Saito, ibid.,53_, 1541 (1975). 2)R. Diebold, Proc. 19th Int. Conf. Hige Energy Physics, Tokyo, 666'.197 3)F. Muller, CEBN EP preprint EP-79-148. 4)Japanese Balloon Emulsion chamber group, Proc. 16th Int. Conf. Cosmic Rays, Kyoto,6,112(1979). K. Sawayanagi, ibid.,6_, 118 (1979). 5)T.K. Gaisser, F. Halzen and E.A. Paschos, Phys. Rev. D15,2572(1977)• F. Halzen, AIP Conference Proceeding (Bartol Conf.) 49_, 261 (1979). 6)T. Shibata, Proc. 16th ICRC, Kyoto, ]_, 346 (1979). 7)Brasil-Japan Emulsion chamber collaboration, Proc. 16th ICRC, Kyoto, 6, 356 (1979). 8)D. Cline, Rapporteur talk at 16th ICRC, Kyoto, 1_4, 271 (1979). 9)Y. Fujimoto, ibid, 1_4, 308 (1979). 10)Y. Takahashi, AIP Conf. Proceed. i9_, 166 (1979). K. Kasahara, AIP Conf. Proceed. £9, 162 (1979). ll)Mt. Fuji Emulsion Chamber group, 16th ICRC,Kyoto,6, 68,344(1979). 12)Proton Satellite group, Proceed. 12th ICRC,Hoba-t, 1 ,1746 (1971). 13)Mutron group, Phys. Rev. Lett., £2' 974 (1979). 14)S. Miyake, K. Hinotani, T. Kaneko and N. Ito, Journal of Phys. Soc. Japan, 1B_, 464 (1963). Figure Captions Fig. 1 Total production cross-section of p',K*, DD and BB. ISR point is for a(h D>. The upper limit of o(DD) has been also derived based on the muon azimuthal angular distribution at Kolar Gold Mind. Fig. 2 The high P„ hadron cross-section obtained by the carbon target emulsion chamber of Brasil-Japan emulsion chamber collaboration and Y-rays £n ,y ) of cosmic ray events. Points(A) and (B) correspond to Centauro events. Fig. 4 The relation between the Feynman variable X (-p* //s> and C.M.S. emission angle 8* (or laboratory angle 0} for E = 150 TeV. The emission angle of the hadrons with P =0,1 and 0.4 GeV/c with corresponding X can be found from this graph. Fig. S The schematic view of the muon pencil beam. Original photo is available in the reference* 143 and in the text book written by S. Hayakawa entitled "Cosmic Ray Physics",page 500. Fig. 6 The decay probability into muons from pions and kaons decreases with the increasing of the parent pions and kaons. Only less than a few MeV is allowed. cr (pp-MX) Fig. 1 10mb 1 \~ 100}iM- 10 h CioliaHi i I i L _l__i i L_i 1 Ip 10 100 GeV 1 10 100 1000 TaV tc 10 E^TeV) 5o 9 150 (JBC) o A 136 (I.SR) i O 0.251 1 X 0.106 f (MAL) "•afà • 0.051 J LU. 1Q1 bio. LU 105 id: i<5 0 \ kV". iô6 t 10 >l -i f. •t i i i 0 0.5 1.0 1.5 2.0 25 3.0 3.5 40 PT(GeV/c) 10 % hadron Fig. 3 PT = 0.1GeV/c = 150TeV 10*0* (1mm) 9 1 / mu i / / i H / ///// / / / / / i i mu r i r ) / i i mi i i r i i i i lllll I I 1 / / i, I mn i i i / / i i inn i / i / i i 1.3 i lull i i I / / i . mu il r / / I Hill 1 1 1 ' / I ; Hill II 1 / / i / Hill i / / i i i / ///// / / i - / / i / mil \ I / ; i / mu ii i ~ i i / mu II i i / I / mil i / / / / 1 / Hill II 1 1 / i / mu II i i / i - / urn II i i / i / inn II i i i i 0.6 ; inn \ l I i I \ -9 Fig. 5 1 -4 -8 -12 -16 -20 10 10 10 10 10 Prob. Pig. 6 B - PARTICLES Harald Fritzsch Recently an enhancement in the channel J/f Kir has been observed at 5.3 GeV ', which is a possible candidate for a B meson 213' 1 . If this turns out to be correct, it means that it will be very useful for future experiments in hadronic physics to develop techniques in order to study thoroughly the final state in J/r production. It could well be that the whole spectroscopy of B particles, including the B baryons, can be investigated using the production of ô/f as a very sensitive trigger. It may turn out that it is easier to study the B particles in hadronic collisions than in e e" -annihi lation, a situation completely opposite to the caseof charm. First let me make a few general remarks about the b quark. Assuming that the fa quark is a color triplet (an assumption we! 1 supported by the present knowledge about the b quark from the y spectroscopy and the e e~-annihi1ation experiments) we expect the existence of the 0" mesons B~ (quark composition ûb) and B° (quark composition db) as well as the Û meson B° (quark composition ib) with the following masses: M(B)«s5.2...5.4 GeV, M(B") - M(B°)*»few MeV, M(B°) - M(B) fs 150 MeV. Furthermore one expects the existence of b flavored bary ons (quark composition udb, ...). The lightest b flavored baryon will be A? (quark composition udb). Furthermore there exist the baryons ^h>2"h'^b (luarl< composition uub, ddb, udb respectively). In a naive approach, based on simple estimates of the chromomagnetic interaction, one expects the mass diffe M t0 be of tne rence M (2"b) * Mk) order of 200 MeV, i.e. + w are the strong decays ^h~*" Ah allowed. Thus the A, state is expected to be the only "stable" nonstrange b flavored baryon of b charge * I which is stable. It will be somewhat difficult to observe the b baryons of quark compo sition usb, dsb, ssb, etc. in hadronic collisions* and we shall not discuss their properties here. Thus far not much is known from experiments about the weak interaction properties of the b quark. However it seems excluded that the b quark is absolutely stable since no stable particles with a mass of the order of 5 GeV have been observed. It is assumed by most theoreticians that the b quark is the charge (- 1/3) partner of a new weak doublet (.). Meanwhile we know from the e e -annihilation experiments that the mass of the tquark is not only larger than m., but more than about 15 GeV. Thus the weak interaction properties of the b quark are somewhat similar to those of the s quark. Like the s quark the b quark can only decay via mixing with the lighter quark of charge - 1/3. I would like to mention at least one unconventional possibility for the b quark decay, which may be realized in case the t. quark does not exist, namely the possibility that the b quark is (mainly) a SU(2) singlet. In that case it can decay only via the neutral current interaction, e.g. b —* s + (uu, dd, cc i /Jyu, v v-,. . . ), If such flavor changing neutral currents should exist and if the b decay proceeds exclusive ly via such channels, one should be able to detect them rela tively soon, e.g. in e e" annihilation by looking for p+ u~ pairs produced in the b decay. Throughout my talk ] will as sume that the weak interaction of the b quark is given by the conventional six quark scheme. In general the b quark can mix with the s and d quark. However an appreciable mixing with the d quark would wreck the universality of the p-decay interaction, and it can only be rather tiny. No such stringent constraints exist for the mixing between b and s. Many people have speculated about a connection between the weak mixing angles and the quark masses. - 116 - In such theories the heavy quarks decay in weak cascades, e.g. t -i b -4 c -> s, i.e. one expects a relatively strong mixing between b and s, and a much smaller one between b and d, in accordance with the constraints imposed by universality. Let us make the assumption that the b flavor changing charged current is (Be), i.e. we neglect the (bu) current. Furthermore we assume that the decay of a b flavored particle can be treated such that we consider only the decay of the b quark, and neglect all other quarks in the corresponding particle. Such an assumption seems to make sense in treating the 0 decay while there is evidence that in the D 41 decay the additional quark is engaged actively in the decay. ' Let\us consider the weak decay of a b quark. The b quark will emit a virtual W" -boson and turn into a c quark. The W"-boson disintegrates into a fermion antifermion pair (either Vt , or vp << , or \"cr", or ûd' (d' = d cos 8 + s sin 8 , B —CabibbD angle) or cs' (s' = - d sin 8 + s cos 8 ). Subsequently we shall set 8C = 0, i.e. d' = d, s' = s. Of course, the decay modes involving a (cs) pair will be somewhat suppressed compared to the decay modes involving a (ud)-pair, due to phase space. We have argued that the decay modes involving a (cs)-pair are by far the most interesting decay modes, and in particular the ones which allow for a realistic possibility to discover the B mesons and to determine their masses ' '. Our argument goes as follows. If the virtual W-boson disintegrates into a (cs) pair, the cc-pair in the final state can give a cc-charmonium state (e.g. J/V)- Thus e.g. the B" meson will have a certain chance to break up as follows: B" —>7/t + K~, 7/V + K"n , y'+ K~ etc. Since the J/U-meson has a sizeable branching ratio to decay into/* y , decay modes like 8-* 7/VtX are easy to identify. Furthermore the J/lf state is very heavy, and the amount of multiparticle phase space avail able in the B decay is greatly reduced in case of a J/Vemission. For this reason we believe that the B decay modes involving a J/fmeson are the ones which can be used to determine the masses of the B meson. - 147 - Of course, it makes sense to look for such decay modes only if the branching ratios for them are not tiny. In ref. (2,3) we have pres ented arguments that the branching ratios for those decay modes of the B mesons involving a J/Tfstate are relatively large, at least large enough to be measurable. At first we estimate how often the b quark is expected to decay weakly by emitting a cs-system. If we neglect the c quark mass and the IT mass and use the free quark approximation, we obtain /7b-*c + c + s) / P(b->all) = 1/3, taking into account the possible decay modes b->c + c + s, b->c + û + d, b-^c +v> + e , b->c + i, + M~, b-vc + vt + t" (note, that the qq-decay modes count three times because of the color quantum number). There will be a kinematical suppression of the cs-decay modes due to the large c quark mass. In order to take into account the quark mass and T lepton mass effects, we use the results of ref. (7), which were derived for heavy lepton decays, and use the values m. = 5 GeV, m = 1,2 ... 1.5 GeV,ms*=0.5 GeV. One finds: f(b-»c* I + s)^14 _ 20%j T(b-*-c + all) depending on the value of mc used (14 % in case m =1.2 GeV, 20 % in case of m = 20 GeV). We neglect a possible enhancement of the nonleptonic b decays due to gluon corrections which is expected to be small (see, however, our discussion of the B° decay below). Thus we conclude that about 14 ... 20 % of all B decays should contain a cc pair. The next question we try to answer is the following one: How often does the cc pair lead to the production of a charmonium state, as com pared to the production of a final state consisting of charmed parti cles? In order to answer this question, we use a method similar to the one employed in order to estimate the rate of charm and charmonium production in hadronic reactions. One expects the production of a charmonium state if the invariant mass of the cc-subsystem is less than (2 MD)w3.7 GeV. Otherwise the final state will contain a pair of charmed particles. - 148 - In a free quark model the invariant mass of the cc subsystem in the b quark decay is a function of the momentum of the s quark emitted in the decay. One has 2 z M(cc) = (mb- /«ÉTf) -f\. Using the "constituent quark masses" nv»-4.8 GeV, m =0.5 GeV, m = 1.5 GeV we can calculate M(cc). For p <0.8 GeV one has M(cc)>3.7 GeV. Note that p can vary from 0 (M(cc) = 4.5 GeV) to its maximum value of 1.4 GeV (M(cc) = 3 GeV). The details of the momentum spectrum of the emitted s quark depend, of course, on details of the decay mechanism (in particular on uncalculable strong interaction effects). However, one may'^expect that the momentum spectrum is roughly of the form given in the free quark model. Here the momentum spectrum is such that rel atively large s quark momenta are favored (the spectrum is similar to the electron momentum spectrum in the^j-decay, which increases almost monotonically with the electron momentum}. Thus we may expect that about 60 •;: of all b quark decays proceeding via a cs emission will lead to the production of a cc meson, and only about 40 % lead to the produc tion of charmed particles. We shall assume that this is the case. We mention the following decay modes of the B mesons involving ce mesons. I. B-» ^c K, 7eKli", ...; II. B-+J/^ , J/y K"iT, ...; III. B-A * K, .. , ( x stands for X (3.415), %.(3,508), or X(3,555)). IV. B -> y' K, y' Kv,... V. B —» i. K,xkTT,... C% : 1" p wave cc state, expected mass about 3.35 GeV). - 149 - Of course, we cannot calculate exactly how often a J/f meson is produced in the B decay. For example we may assume that all charm- onium states below charm threshold are produced with probabilities which are roughly equal. In this case one expects about 30 i of all decays involving a cc meson to lead to a J/1^ state (either direct ly or via a sequential decay likef~^ J/^+ IT /ÎT" )• Thus we obtain finally: |"*(B -»J/V- + X) • , .. depending on the value of m used in the calculation. Since the pro duction-^ aO/îf state leads to a very clean signal, it seems feasible to use the J/'î/'production events in order to investigate the details of the B decay. The momentum of the (cc) system emitted in the b decay is equal in magnitude to the momentum of the emitted s quark in the rest system of the b quark. The latter can vary between ^0.8 GeV and~1.4 GeV. Thus we expect the momentum of the J/^ meson emitted in the B decay to be of the order of 1 GeV (in the rest system of the B particle; we neg lect the motion of the b quark inside the B meson). Thus far we have concentrated on the inclusive production of i/~f mesons in the B decay. In order to determine the mass of the B meson, it would be most suitable to investigate a decay like B-fô/tf* K or B -» J/ Y + KIT. The branching ratio for these decays is certainly smaller than the inclusive branching ratio for B-»Y(J) + X, and depends on details of the strong interactions (e.g. form factors). Nevertheless we expect that e.g. the decay mode B-»J/Tf'+ KIT consti tutes a non-negligible fraction of all decays of the type B-»J/Y + K + X In order to say something about the hadronic system X, we consider those decays where the J/1/1 is formed directly. We assume that the JJtf state is formed before the final state interaction between the light u or d quark (the second constituent of the B meson) and the emitted s quark sets in. Since the 0/if state is relatively small on the typical -13 hadronic scale of 10 cm, this may be a good approximation to the real situation, Furthermore, we neglect the motion of the quarks in side the B meson and the binding energy of the quarks. Thus we can describe the decay B >—^ j/f + X by the effective b-quark decay b •—» J/V + s* In the rest system of the 8 state we can easily calculate the momentum of the J/f and the s-quark: p «: 1.5 GeV. Thus the invariant mass of the system consisting of the û(d) and the s quark which is recoiling against the j/y is given by which for H„ = 5.3 GeV and p » 1.5 GeV is equal to 1.1 GeV. Thus the hadronic system recoiling against the J7V- state is given by a system formed by a s and a û or d quark of invariant mass~-l.l GeV. We expect fiat this system consists mainly of K'tC, with only a small contribution of Kirirjnote that the first resonance decaying into KITT" is 0 £l28c0 ). We conclude: X = T . The decays B-^J/lf + K, B^J/Tf + KTTT are expected to be suppressed. The (Krïï*)-system in the decay B-^J/l^ + (KIT) has an invariant mass of about 1.1 GeV. The following decays are possible: B~(ûb) -» J/V l"T° -» j/y- ifir. All four decays mentioned above may occur with equal branching fraction, which within the approach discussed above should be of the order of a few %. - 151 - We can carry out a similar analysis for the decay of the B (so)- state, which is expected to have a mass of about 5.45 GeV. Here the system recoiling against the J/J/" state consists of a (is)-pair, which has the invariant mass of 1.3 GeV. We expect that the leading decay modes of the B° state involving a J/tyare: B° ->J/ Jf KK B°-»J/ V \'!r~i~ We do not expect that the decay modes B°-*J/^, B°-*J/y q, and B, —> J/^ 1£' play a significant rôle. In à similar way we can treat the decay of theA h . After the decay b-* J/Tf+ s the system consists of a diquark (ud) essentially at rest in the/T rest system), and a J/ V moving with momentum p ~- 1.5 GeV in some direction, and a s-quark moving with momentum p in the opposite direction. The invariant mass of the system recoiling against the J/lf and consisting a the s quark as well as the (ud) diquark is ~1.7 GeV. We find it unlikely that this final state consists of config urations likeAIT , ATT IT , since the s quark moves away from the (u d) system with high speed. Rather we expect that the s quark fragments in to a K meson, and the final state should consist of NK or NKTT . Then the best way to look for the A h state would be to look for the decay mode A b—> J/*Y pK". The associated branching ratio should be of the same order as the branching ratio for the decay B -=» J/Vf KIT . A possible way to treat the decay b-» J/1/' + s in a more quantita- 61 tive manner is the following one '. We consider the effective Hamiltonian of the b decay and perform a Fierz reordering (bc)(cs) = 1/3 (bs) (c"c) + 1/2 (SA,, s) (EX,-c), \_\: SU(3) color matricesj. In a simple - minded approach we may evaluate the matrix element < b | H | J/y- s> by writing: < b / (be) (cs) | J/f s > = C b | 1/3 bs | s > < o | cc| J/», - 10 - i.e. we disregard the second term involving a product of color octets. Our procedure is similar to the one used in the calculation of the decay T —» ^r $• The decay rate for b —* ô/T-* s is given by the J/"¥- decay con stant, which is measured in the leptonic off decay. One finds: B (b —» ô/f + s)œ 1 ...2 %, a value which is somewhat smaller than our previous estimate. Note that in this approach we have disregarded the term involving the color octet product. The question arises if we can da so or not. We believe that we have no justification to disre- 21 gard the color octet term ' since a color octet can be changed without great difficulty into a color singlet by adding a soft gluon. We would like to argue that the color octet term should not be discardeo', but acts essentially with full strength. In that case we may simply use the current - current Hamiltonian for b decay forgetting the color quantum number. Effectively this means that we should multiply our pre- vions result (B~l... 2%) by nine, i.e. 8 (b —» J/>+ s) ~ 9 ... 18 ',.. Thus we obtain a very large branching ratio, which comes close to saturating all b decays of the type b —» s ce. All ce states, except the J/Tand the 7^ r, contribute only little to these decays. The reason for this surprising fact is that we have assumed to treat the decay b —> s J/7- like the decayT —> v£ p, i-e. we neglect the strong interaction of the b and s quark {for example, we have neglected decays like b -» F+ c). It is somewhat difficult to estimate these effects, but we believe that our order of magnitude estimate is correct, i. e. B ( b -* s + J,'> ) « 10 Ï. In the experiment of ref. (1) one estimates: B 6" (BB) ~ 1 nb. Using B (B -» J/>K0,ir ~) a 5 X, which follows from the estimate above, we conclude that the cross section for B production inlT - N collisions should be of the order of 20 nb, a value, which is some what large compared to QCD estimates ', but not inconsistent with the estimates given in ref. (8). - 11 - - 153 - I would like to conclude with the following comments: a) Recently it has been argued by various authors that the oberved relatively fast decay of the D°, compared to the D decay, may be due to the annihilation of the (ûc) pair in the D° under the participation of gluons (see e.g. ref. (4)). The same effect may repeat itself for the B (annihilation of (db) into (ûc)) . According to the estimate given in ref. (1) we expect that the ratio T (B~) /T (B°) is of the order of 2...3. In this case the decay B -> J/> ICrT, which cannot result in the annihilation's suppressed and should not been seen as clearly as the B —* J/vK IT decay. In the same way theAb decay may be affected by the decay via annihilation: bud—> cdd. Asa consequence the de cay/A b —* J/7-N K should be suppressed, if the annihilation dominates. b) Although we believe that the best way to look for A b is to study the decayA b—> J/r pK", it may be worthwile to investigate the decay A i,—*J/H/ A T . Since the s quark is emitted lefthandedly, the emitted A particle should be polarized. c) The decay of the B° state may also be dominated by the annihilation process (like the BG). In fact, we can say: If the B° decay is dominated by the annihilation of the (db) pair, the B° decay must be dominated by the annihilation of the (ib) pair in an analogous way: (lb) > cc. In that case the B° decays into a pair of charmed particles with an invariant mass given by M_o. It will be difficult to see this decay. REFERENCES 1. R. Barate et al., CERN preprint EP 79 - 113. 2. H. Fritzsch, Phys. Lett. 86 B (1979) 343. 3. H. Fritzsch, Phys. Lett. 86 B (1979) 164. 4. See e.g.: H. Fritzsch and P. Minkowski, Bern preprint (Oct. 1979); U.K. Gaillard, these proceedings. 5. H. Fritzsch, to appear in Phys. Lett. B. 6. M.B. Wise, SLAC-PUB -2399. 0. H. Klihn, S. Nussinov, and R. RUckl, Munich preprint MPI-PAE/PTh 50/79. T. Oe Grand and 0. Toussaint, Santa Barbara preprint TH - 18 (1979). 7. Tu Tung- Sheng, CERN preprint TH-2763 (1979). 8. H. Fritzsch and K.H. Streng, Phys. Lett. 78 B (1978) 447. ( Theoretical Prodict ions Tor liigh-r»i--;:4 flavour Production in Hadron-Iiadron Collisions C. Peterson NORDITA Blendansvej 17, DK-2100 Copenhagen <'•, Denmark Abstract A brief review is c:ivcn of current tlicoretic.il ideas on high-mass flavour production in hadron-hadrcn collisions. In particular we discuss hard scattering pertubative OCD predictions and upper limits on cross sections expected from soCt mechanisms, i'e also shortly present some new ideas on difTractive production of heavy quarks and some comments on the existing experi mental data. (Invited talk given at the "Topical V.'orkshop on Torward Production of Ilirh-f'ass Flavours at Collider Hnergies", Collece de France, Paris, November 28-30, 1970.) J.. Int. roduction Al though many expor Lr.cnts have been pc-r formed in the past in order to search Tor char?; in Judronic inter actions it was not until recently direct signals were found '*"' ' . Tho cross sections quoted in these- oxpor insents nro of tlio order 100-500 \-A> for Inclusive D and A production at \/s = 53 ami (53 GeV , These c • ' cross section:-; arc consistent with v/iiat ha:: |-,cen inferred from the bean dump experiments at P - -Ï0 0 tieV/c ' whore the nnoralous ly larçc neutrino product ion rate is assumed to ptcm from weak decays oi charniod particles, i\ salient feature of the Drodaced .' ' ai;:l D jnart Cror,, c the larac cross sections is that they Lend to be produced in the forward re?ion of phase space contrary to what would be expected naively. This feature is shown in f ig. 1 and 2 rcr tho production of ,' and D rcspec- t ivoly . ''rofii IS!! CM per îmonts on Lhe ~ (pp - DN) ; ~ 15-30 |.b ID Qi - y=0 This estir.ato together with the direct data on D pro duction i m\ icate a production cross section which is independent, of. y. '..'ith a central production r.echa- nifiR one v:ouId instead have % (pp - m) I « 200 ub (2) av i y=o if one extrapolates the D dota at; y 2. Noreovcr at least one experiment strongly suggests a diffractive mechanism for the A production. In pure hadronic processes, there are two classes of reactions, which are generally believed to be describ by pertubative QCD, inclusive production of hadrons at large transverse monientum and production of high-mass flavours. In section 2 we discuss the QCD predictions of the latter process ' ' in some detail. It is found that the conventional QCD results are difficult to reconcile with the observed charm cross sections and in particular with the ":-:_ dependence" of the observed A . There are suggestions of how to enhance the charm cross section by considering bound state effects . However, even with such modifications it is very difficult to reproduce the forward nature of the produced charmed baryons and mesons. In section 3 we review the charm production pre dictions by various soft mechanisms, In a Rcggo description we expect st.rong suppression due to the * (12) iov; intercept of the D-mcson trajectory . Also quark parton models have been developed for low p, soft non- -diffractive hadronic interactions. In one of these mutlol-s, Liie i r.n[incntgtion model , the forward jats proiuioed in kadronic collisions are identical to those of the leptcinduced reactions apart from hard brems- strniilunn effects. Thus the probability PlQQ) to pro duce a heavy mass QQ-pair in a hadron induced jet can Le ci} I i nu Led : row a nonpertubative jet model, e.g. the Schv.'inncr modi-'], in which it turns out that P(cc)/Piuu) ~ 10"10 I Uoncv a fragmentation mechanism is out of question. In anoii'.or rcodel for hadronic forv/ard spectra, the iccoirbir.ation model t the valence quarks do not ÎI.'IÎKT-JM inU'r.ictLOP. ;•.(• recomhine with the sea to make cbs^rv.-ibl e hadrons. This sea need net be identical to t ho '.<::o o] t:.'. incnrii nci hadron, but could bo enhanced by i .•'. .1 :-ii •: coli is inn described by pertubativc C.'CD, TIK ch.irn- pn duct if;n cross section ia in th is case then qiven by the per tu bat ivc QCID value. Details con cerning c.n. roynrcan x-bchaviour cannot bo predicted since tliis node] contains too many unknown parameters, but it sccjr.s '.'ury unlikely that the forward region proper i u*s c-: Lliis model are those of the observed •xp-spectrû :.f the charmed hadrons. Un fortunate 1 y our theoretical knov.'l cdqc about J - 159 - high mass diffraction in nencral is scarce. Concerning high-mass flavour diiifractivc production one might give duality arguments that such production again is suppressed by the low D-meson trajectory intercept. In section A ar.c J we discuss diffraction into states ccntaininq heavy mass flavours both in terns of well established folk.].ore and with regard to some new ideas. In particular we briefly outline a now model in which a hadron is a superposi tion of Pock states which exist on a long tire scale, contrary to what is tho case in pertubative approaches. Some of those state H contain heavy C"> pairs. These heavy quark, states should be smaller in size and hence have a relatively small absorbtion cross section. Consequently these states wi11 bo more emphasized in diffractive channels. This approach is very promising and contains many predictions for various processes. "inally in section fi we discuss the experimental data from a layman's point of view. In this connec tion we in particular emphasize the importance of a presice measurement of the diffractive production of orci inary .". ' s . - 160 - 2. Hard production mechanisms As far os the hadronic production of hidden heavy quark states leg. Oi Y ek. ) is concerned the pertuba- tivc QCD approach has been quite successful. The various diagrams contributing to e.g, ^-prod,uction are shown in fin. 3. It turns out that the gluon amalgamation subproeess (see fig. 3a) o + g • ^-state » i/i + y (3) is essential in ordct to account for the experimentally measured proton induced cross section. Due to the large fraction of hadron momentum carried by the gluons, t;his subproegss is in fact dominant, which explains the absence of observable •',• ' -production in hadronic colli sions, (It has also been reported that in the reaction PP " -,'' \ at /s= f>5 fioV 43" of the observed v's are accom- (1 7) paniod by a photon .) This gluon amalgamation sub- process has also been used to estimate glueball pro duction in hadronic collisions . Tor the production of hoavy quark pairs {QQ) above threshold (e.g. DD-productioni wo expect contributions from the subprocossos (see f ig. 4a and b) QO -> OQ Ma) gg - OÔ (4b) and in principle also from the flavour exitation pro cesses (soc fig. 4c and 4d) cjQ - qO (5a) gQ - gQ (5b) These latter processes could in principle give substan tial contributions ' but the magnitude is quite sensi tive to the initial heavy quark distributions, which are unknown. Disrenarding these flavour exitation processes the process 4b is the dominant one in tlv.' pp case and iL has been -onsidered by many authors ' ' The cross section for the reaction A+B •*• QQ - X is given by r A( o2)r Btx ,Q2) [ dx, cb 2 V 2 2 2 a(s) X1*2SÏ'%2 Xl"2 (6) where s and s are the c.m.s. energies for the total process and the subproccss respectively. F_ (x,0 ) are the structure functions of the incoming hadrons and o(s) is the cross section for the subprocess, An important feature of oq. (6) is that the integrand is large for small x.. Therefore the heavy quark produc tion predominantly occurs close to the threshold with values of /s in the region where structure is still observed in the e e"-annihilation cross section. Hence there should bo bound state effects, which one has to ignore and ho;- that Hit",' arc smear L'U ovor in the cal culation. The medicLion of ref. 3 of this kind is shown in fig. 5 for the charm case. (The result is not very sonsi tive to the choice of the glqon distributions used by the various authors.) Usiny fli = 3 .r j c>v\ cue typically obtain» -i cross sec tion of the order 20-30 i,b at IS:* nnnnjiea (.see fiy. 5), v/hich is not sufficient to explain the existing data on D and A production. (In np collisions the cross section is higher due to a substantial contribution form the subprocoss 4b.) The xF-distributions of the produced c-quarks are as s te en as the incoming gluon distributions, vrhich is hard to reconcile with the forwardly produced A and D . Uov.'cver the x„ predic tions are compatible with the contrai production of charmed mesons as inferred from the observed e/-n-ratio at ISR. In fig. 6 wo also show the cross section for bottom and top production assuming a mass m.=15 CeV . In ref, a 'somipertubativo' alternative is suggested based on theoretical observations in photo- production. It is known that a QCD pertubative calcu lation of the cross section for the process YP •> cc X (7) yields the same asymptotic value as the Vector Dominance Model (VD*-1) estimate. A biçy difference between the approaches is the threshold behaviour. Contrary to the pertubative approach the threshold behaviour of the VDM approach is nicely described empirically by the formula "thr. o(YP - cc X) * o (1 (8) One can therefore hope to improve the threshold behaviour in hadronic heavy flavour production by relating the charm photoproduction cross section to the gluon-produc- tion cross section (see fig. 7) o(gp - cc X) O) The hadronproduction cross section is then given by convoluting o (cjp -• cc X) with the gluon distribution function G , (x) of say the proton g/p o(pn •» ce X) = 2 • C • dxG . (x)a(vP * cc X) *»» ° - JtvW^, is essentially the ratio between tlic electromagnetic and QCÛ couplings. Using the VDM formula (see eq. { 8 )) n for CTIYP * cc X} and G /p(x) = £^r (1 - x) ,n=S the resulting estimate for charm production is 170 ub and 200 |jb at SPS and ISR energies respectively. It should be emphasized once again that the key difference between this approach and the pertubative one lies in the diffe rent threshold behaviours. The major objection to this approach is that the QQ pair in fig. is a color singlet whereas that of fig. 71» is not. Therefore the similarity between fig. 7a and 7b is questionable. In fact the QQ pairs in fig. 7b need not even be a bound state. 3. Soft nonpertubative mechanisms In Regge language the hadronic production of charmed particles involves D*-exchange (see fig. 8) Due to the low intercept of the D* trajectory (a *(0)« -2 - 2.3 yith Û'D*= 1 CeV ) this process is strongly suppressed relative to e.g. strange particle production by a factor s2Aa ~ lo"5 (at ISR energies) with effects to give rise to furthor suppression. Concerning the longitudinal behaviour an estimate is possible in 2 2 the fragmentation region (sA' and b\ large) in the triple Segge expansion framework (see fig. 9). In practice this kind of expansion has worked veil f.or 2 2° M > 3 GeV and s A';*" > 2 in other reactions. ?or the process pp -> A '.< (fig. 9) one gets E 4^ (op - A X) (11) np(OÎ-l / 2^plt)-2uD* (0) (kin. factors] • a " ['•—1 4^- (np - A X) u (1-x,,)5 (12} d->p ' c which is much too steep as compared to the D data. Next we discuss charm production in 2 models, which have had some success in describing hadronic low P^ nondiffractivu reactions, the fragmentation model and thu recombination model. A. The fragmentation model In this model ono of the valence quark of an impinging hadron fragments into observable hadrons in a manner identical to what is the case in lentoinduced reactions (e.g. GO • hadrons and ep -* ep + hadrons) apart from pertubative QCD corrections. This similarity is fullfillcd as far as multiplicities, P(qq) = \u\2 (13) where D is the penetration factor (24 ). V-e now calculate D by means of semiclassical methods. Let x be the distance between the quarks. Then the conjugate momen n a tum is given by o = (P1+P2Ï/?' I potential U(x) = ' " 2 U - kx we get n = /(kx) - m 2 , m being the quark mass. Now the penetration or tunneling factor D through U(x) is given by D = cxxpp ipdx = xp( - \ \p\ûx) = exn[ - f /m2-(kx)2 dxj (14) / m2 f / T , \ ( m2n\ (p = ip; the moniontum is imaginary when tunneling through U(xl). Itonco we get from en. (13) using k = ^7-, where a* = 1 GeV'"2 2 2 P(qq) = oxn(-:i m(j ) (15) Using the consistent quark masses m = m, = 350 iMeV and m = 500 ."'cV one obtains with this semiclassicnl estimate IMSS) , 2, 2 2,., _ _ PT^QT = cxp(-- (ms -mu •))* 0.3 (16) which agrees rather well with the phenomonologically determined value 0.5 (25 ). The corresponding c-quark suppression using in = 1.5 Gc.\' is given by Pfcc)_ r(ua) (17) Thus we conclude that heavy nuark production is extreme ly suppressed in quark jets. In this model the fast valence quarks are unaffect ed by the interaction and reconbincs afterwards with the sea, whicli need not be Identic ni v;i th the original sea. It could e.fi. be enhanced by a hard collision (see sect. 2). The sinale particle spectra Tor mesons (ab) with •£ 5, 0.5 are given by ^£ a f Ë1 ^2 riv x ) "U x \1 (181 ( t x N, Utj dx J X]_ ^ ' VV -• -•1' 2' > where F (x, ,x., ) is the 2 nuarï: distribution function which can be written l-'tx.,*,} = r* (XiJïVtXjJ.'.il-x.-x-ï (19) recombination function R(x,,x2,x) is unknown, but has been parametrized reasonably to fit inclusive u" and K" data, V-'tth this paranctrization the inclusive I) -spectrum is not reproduced. As far as the cross section is concerned the hard scatterinn processes in sect. 2 sets the magnitude of the prediction of this model. 4. Diffractivc Production One might argue that one way of avoiding the above mentioned D -exchange is to produce a heavy system M ditfractively (see fig. 10a), which sub- sequeni.iy decays into charmed particles (12) . However this process is in a way equivalent to p? scattering which via duality contains D*-exchango when charmed particle production is concerned (see fig. 10b). In ref. this argument was disregarded and the decay 2 of the excited state fl was considered pertubatively, and hence the resulting charm suppression is powerlike o(t.c) ,ra >2 ^ — * (nhase snace sunoression) (20) ni» VlV This approach is however not theoretically quite satis- fying since one expects the high virtuality II*" to be equally shared among the constituents rather than concentrated on one or two, which is needed in order to perform the pertubativo calculation leading to eq. (20). One would rather expect the high mass system to decay in a Hagedorn manner, i.e. - 170 - exp(-2MD/160) which again results in a fairly strong suppression. 5. An intrinsic charm of the proton As emphasized above experiments indicate that a short time scale pertubative oicture of heavy quark production is not adequate. We have recently explored the consequences of having an intrinsic (long time-scale) charm component in the proton. This means that the rock space decomposition of the proton wave- function contains a nonneglible uudec component. Such a picture would be rather compelling if it is indeed true that charm can bo produced diffractively. At high energies only a small momentum transfer is needed to out the charm component on-shell. The relative magnitude of such a uudec component cannot presently be theoretically predicted. Let us instead focus our attention on the momentum distribu tions of the quarks in the uudec component. In a long time-scale interaction the quark velocities tend to equalize. This statement can be made more precise by considering transition probabilities in old-fashioned pertubation theory P(p - uudec) -u i— — (221 (* 2 " ^ 2 2 2 e where mj, • = m. + pj. . and we take i = . ,5 for cc. In what fol'ows we neglect any rromentum dependence of t 2 numerator. In the limit of very heavy quarks m^ - *>> m 2 ,m.2 (i=l,2,3) the momentum distribution becomes 2 2 5 P(x,, ..., xr) = :i — — fi(1 _ J x ) (23) J (xt,+x&) 1 whore N = 3600 is the normalization determined by 1 dx1...dx5 P(x1-•-x5) = 1 The charmed ouark distribution obtained from en. (23) 2 2 .x ) - i N x5 [i(x->;5)U+ 10x5+x5 )-2x5(l,x5)lni] L 5' (25) is shown, in fiif. 11. The average is ':xr> = j. This should be contrasted with the light vuark distribution 5 P(x1) = Gd-x^ (26) with the average 6. Summary It seems to be clear that the data on forwardly produced D and A are neither described by pertubative OCD nor any conventional soft schemes. However the (271 centrai production of D-mesons fits nicely with QCD . It is therefore plausible that there exists two compo nents responsible for high-mass flavour production, a central production one described by nertubative QCD and a cliffractionliV.c process. ?or the latter compo nent there are some encouraging ideas as denonstratcd in tlic previous section. I would be a most valuable guideline Tor future theoretical dcvcloorcnt to net established whether the /. ' s real t v are d i f Tractive 1*' nreduced . This c could be accomplished by e.g. cxr.cndina the rapidity cjap rcqion in single dirfractive dissociation experi- ( 2 ) men is like rof. . Also detailed x -behaviour and 2 2 data ciown to .': = ?! . would be very interesting. Concerni ng .''-production one estimates in rcf . ( 19 Ï that the di f Tractive part is 'v-10'ù of the total incJ astic A-cross section, i .o. ^ <10 0 lib. This is tlio same order of rriagnigude as the '« -production ('.) . It i.s thus very important to neasure diffractive A-production to see to v:hat extent the diffractive high mass —5 tail is built up by hinh mass flavour states (including strangeness) . Kciercnccs: 1. 0. Rrij.-i-il ct ill., Phys.Lett. SUi [1975) 250. 2. K.L. Glboni ct al., Phys.Lctt. S5U (1979) -137. 3. M. Lockman et al., Phys.Lctt. 8_5J3 (1979) -14 3. .] . !). Drijard ot nl . , Phys.Lett. £3D (1979) J52. r;. p. A! il.ran ct a;., Phyr, .Lett. 7 jn U97CJ 13--.; T. lianr.l c: al., pbys. Let t. Tjjj C373) 13-j ; P.C. Bcsetti et al., Phys.Lctl. 7jUî (1978) 103 . 6. !•.!;. litir.scr ct a].., Nucî.Phys. B1J_3 0976) IE!); ;.. L!au::i c; al., Phys . i.et t. C C i ! Î197C! -'25; •1. Dar'-:ic ct al., Mucl.Phys. P.132 (1973) 29. 7. '.;..'l. CeLst, Talk niven at the SLAC Suir.r.or institute on Particle Physics, Stanford 1979, L'LP.M/'L'P 79-129. o. 1;.:;. r.corci et ai., Ann. cf Physics 11 i (1978) 273. 9. 13.L. Carbr;dyc, Kucl.Phys. iH2I <-3'9) -'29. 10. T. Tunij-Khcnç], Til . 2763-CCRN . 11. II. l'ritïsch and K.I1. Strong, Phys.Lctt. 7jm (1978) All. 12. V. Uarçc-r and I!.J. H. Phillips, Phys.Rev. 012 (1975) 2023. 13. p. Anderson, CI. Gustafson and c. Peterson, Phys. Lett. TJX (1977) 337. !•:. K.P. Das and ii.e. llv/a, Phys.Lett. ÇBJ1 (1977) 459. - 175 - 15. S.J. Brodsky, P. Moyer,C. Peterson and ',1. Sakai NORDITA preprint in preparation. 16. Sea e.g. C.E. Carlson and R. Suaya, Phys.Rev. D18 (1978) 760. 17. J.II. Cobb et al., Phys.Lctt. 215 (1976) «97. 18. C. Peterson, NORDIVA-79/]S. 19. S. Erhan et al., Phys.Lctt. CDU (1979) 447: F.VI. Biissor et al., Phys.Lctt. C1B (1976) 309. 20. Anne Kcrnan, Proc. of 1979 International Symposium on Lepton and Photon Interactions, FNAL, Batavia, 111., Sept 1979. 21. p. Cnpiluppi et al., Nucl.rhys. B70 (1974) 1. 22. A. Chilingarov et al., Phys.Lctt. 8_3B (1979) 136. 23. Casher, Kocjut and Susskind, Phys . Rev. Lett. .3_i (1973) 792; D. Anderson, G. Gustafson and C. Peterson, Z.Physi C, Particles and Fields 1 (1979) 105. 24. il. uohr and II.B. Nielsen, NBI-IIE-78-3. 25. R.D. Field and R.P. Foynman, Nucl.Phys. B136 (1978) l. 26. G. Gustafson and C. Peterson, Phys.Lctt. 67B (1977) 01, 27. 1!.M. Geist, La lie at this meetinti. Figure captions d:;/dl>- I for A at 5 3 CeV l J> and .', at 53 • F c ( °) and G3 CeV for the 3 experiments ACH"\"K , The figure (20) is taken from rof. The smooth curve is a compilation of do/dx for inclusive K -in'oduction at /s" of 53 CeV The solid c ireles are D cross sec tions from rofs- and . The Ciourc Firj. 3 Madronic «I1-production via a) 2-rjluon nmalcian.ation b) nuark-nntiquark annihila tion . Fi'i. 4 Loves t order diagrams for the a) quark- -quark bl cjluon-q]uon subproccssos and c)d) the fJnvour cxitation subprocesses. Cross section for pp -• cc from ref. i Fig. 6 Cross section prodictions Cor pp -> bb and pp -* tt from rcf. Fig. 7a Photoproduction of charm. The photon couples virtually to a bound cc-pair, v/hich scatters off the hadron to produce the final hadronic system including a pair of char.'icd particles. Fig. 7b 01uoproduct ion of charm, '"he yluon couples v irtual )y to a bound cc-pni r, which scatters off the hadron to produce the final hadror.ic system including a pair of charmed particles. Fig, 8 Inclusive associated production of charn in a D -exchange mechanism. Fig. y Triple Reggo expansion for the reaction pp •> AcX. Fig. 10a Di ffraefcive production of a high mass state subsequently decaying into charmed particles. I _J Pig. 10b pEi-scattoring into the state M and the dua L process containing D -exchange. Fig. II The c-quark and u-quark distribution in a !uudcc> state. I-'iy. 12 IVynnan x distribution of A in the reaction vn -* A X. I r - 179 - i—i—[ i r T—i—i i i r dcr dlxl OA° (VT=53 GeV) + (mb) @A C (v7= 53,63 GeV)- 10.0 ACHMNR 0.1 0.01 J L 0 0.2 0.4 0.6 0.8 .0 IXI Fig. 1 10' f 1 1 1 -r = \/s = 53 GcV O0+ \ K" 10 - 7 da- ~dx 1 mb) \ 1 J Z CCHKA CEKM- EIII-5.'.:LH \ 10"' - \ Id2 I —J L_J 1 I C 0.2 0.1 o.c 0.0 X ri". 2 / V rirj- 3a Tig. 3b X rig. 4a J/ Fig. Fig. 4c X. Fig. 4d ji Fig. 5 rig. 6 ^zp»**^-. rig. 7b A -—^ A< o-(p'P -A+X) = Disc p ^ p ^ J- 1V 2-L À. IX- *k ^~r D" tr FiÇJ. 8 Fig. 9 ../"" rig. 10a -Xc "Ac X M2 Fig. 10b T—"1 - 185 r T-y\ I'iq. 12 VY versus Drell-Yan_effect in pp orjpp storage rings C, Carimalo, P. Kessler and J, Parisi +' Laboratoire de Physique Corpusculaire, Collège de France, Paris We want to compare the Drell-Yan effect^ shown by the diagram of fig. 1, with the X*" process, as described in the quark-parton model by the four diagrams of fig, 2. If one considers in particular diagram (d) of fig, 2, such a comparison is quite similar to that between diagrams (A) and (B) of fig, 3, i. e, between electron-positron annihilation and electron-posi tron scattering via the JfY collision mechanism. However, now we are considering quarks instead of electrons. Obviously, the analogy is not complete, since here we don't have quark beams with fixed energy; only the energy of the quark-generating nucléon beams is fixed. With e e" colliding beams, annihilation and jf^effects cross at fs"^= 1 GeV (comparing for instance e e" —&H- Jt" with e e" —^ e e" u, it"; see ref, 1), Qualitatively, since nucléon or quark masses are about a thou sand times higher than the electron mass, we would thus expect the Drell- Yan and the JQTprocess to ÛTOBS, in the case of pp or pp colliding beans, at Ys <£j1000 GeV, We are going to show that this is indeed what occurs. In the double equivalent-photon appro? lation, the yv effect is given by a d&= N(x) N(x') tLX (M ) ci* ci*' Z with *= SEf/Vs, x'= 2Eg,/ïï, «A M ^ XX'S calling M the invariant mass of the lepton pair produced. We are interested in computing the quantity Kith^-^A*-, «d r= M%. In first approximation, at large s and very small X, one gets (for more details, see ref, 2)i &. (zs) ^ **<**- faÇs-j) +) Speaker: P. Keseler where 7„(0) is the value of the proton's structure function at the zero Unit of the scaling variable, :jne thus gets: S- /If "(*•%-'. ..n the other hand, for the Drell-Yan process (both Tor pp or pp collisions), one gets, assuming 2Tto be sufficiently snail in order to have nainly col lisions between sea quarks: ê?'= MB (d.*ff/dHdy)^£2LçS[fjcf (having included a factor 1/3 for color). One thus obtains the ratio This ratio is indeed of the order of 1, setting F„(o) -^0,2 and considering the case: s ^10 GeV2 and 10~5 (il) The angular distribution of the leptons produced (in their c. a. frame, vith respect to the dilepton production axis) is quite different, namely -*— 4 + COS^B for the Drell-Yan effect A -r cos* & for the ~ T Xr JL ,t,*\ YX effect i, e, leptons from the ,^ process are much more fomard-backuard peaked, (iii) In ^processes, the transverse-mom en tun distribution of the dilepton is fairly large; one has indeed for the corresponding average: X In this work, we didn't make any comparison uith dilepton production through other mechanisms. 0) J, Smith, R. Bhattacharya, and G, Grammer, Jr., Fhys. Rev. D ,lj>, 3267 (1977); see fig. 3. (2) C. Carimalo, P, Kessler, and J". Parisi, Phys. Rev. D 18, 2U3 (197S). Other authors who studied the W^ mechanism in hadron collisions are: V.M. Budnev et al,, JETP Lett. J£, 238 (1970); K. Fujikawa, tïuovo Ci- nento UAf 117 (1972); H.S. Chen et al., Phys. Rev. D 7., 11 (1973). Figure captions Feynman diagram for the Drell-Yan process. Fig. 2. Feynnan diagrams for thek'jf process y Vi + !.' —** £. +^ + X, (a) elastic-elastic term; (b), (c) elastic-inelastic terms; (d) inelastic-inelastic term. Fifi, 3. Feynraan diagrams for (A) e + e~ -^ it *-/t-~r (E) e' +• e" - e ' + e~ + t+ + u", 3 6" ï (:: d^dK dy) _c computed for: —• —• —- •- Drell-Yan process, p + p —?• LL + b~ + Y — Drell-Yan process, p + p —> u,' + k," + •< _ _ _. _ w process, s = SCO CeV2 _» — _ yy process, s - 64.0 OOC GaV~ — ,Jpr process, s = 2 10r d .V2 ( R9. d ft?- £ 10 vr* 10"3 10"2 10-1 Ma/s FIG. 4 Invited talk presented at the Topical Workshop on Forward - 195 - Production of High-Mass Flavors, College de France, Paris, November 1979 Monte Carlo Studies of Forward Ag Production in pp Interactions at 540 (Self cm Energy P. Gutierrez and A. Kernan University of California, Riverside Abstract The topology of forward produced A. decaying to T K"p is studied for the UA1 detector at the CERN Proton-Antiproton Collider. Recent experimental measurements at the CERN ISR show a substantial (ilOO IJb) cross section for production of the charmed baryon A in pp collisions at cm energies of 53 and 63 GeV [1]. It thus seems likely that the corresponding b-flavored baryon, A» (bud), my be produced at a detectable level in 540 GeV pp collisions at the CERN Collider, we sum marize here the findings of a Monte Carlo simulation of Ag decays in the UA1 detector [2] at the CERN Collider. For an inclusive cross section o(Ag) £10 ub the problems of implementing an efficient trigger and of minimizing combinatorial background are formid able. Because of this we have focused on the decay mode suggested by Fritzsch [3]: f.B •* ? + X [X = N R,n K n] where X is a B=l, S=-l system with mass around 1.7 GeV/c . The decay se quence AB •» Y + K" + p (1) permits an effective dimuon trigger, and the requirement of an identified «'would reduce combinatorial background. The expected branching ratio for AB - ? K"p is 0.5=; [3]. To date h production has been seen only for Feynman x £ 0.3 [1]. This observation suggests a fragmentation production process in which A contains two valence quarks from the incident proton [4]. At the Collider we corres pondingly expect An and An production at x > 0.3 in the hemisphere of the incident p and p respectively. For the Monte Carlo study we consider An production at x > 0.3. The 2 decay sequence (1) is used with a Ag mass of 5.7 GeV/c [3j, Figure 1 shows the Pj, p. envelop for the final decay products y", K", p for An with x of 0.3 and 0.9 and p-j- = 0. The decay products are strongly collimated in the forward direction, the muons being at the largest angles due to the energetics of 't decay. The mean pj for u, K, p is 1.3, 0.6 and 0.8 GeV/c respectively. Figure Z shows the p, projection of Fig. 1. The UA1 detector consists of a "Central Detector" covering the angular range \0\ > 5° with respect to the incident be?m direction and two sym metrical "Forward Arms" with coverage 5 mrad <|0|< 5°. The Ag decay products traverse primarily the Forward Arm. The main elements of the Foward Arm (Fig. 3) are, starting from the magnet end-caps ; 1) An image chamber (ENDCAP chamber)' inside the end-cap of the main magnet 2) An electromagnetic calorimeter 3) A compensating magnet fully calorimetrized for hadronic calori- metry. Inside the gap of the magnet an image chamber (CALC0M chamber) surrounds the beam pipe. - 197 - 4) An image chamber (ROME chamber) 5) The very forward calorimeter with an electromagnetic part in front, followed by hadronic part and interleaved with chambers to detect the centroid of showers. Figure 4 shows 40 muon trajectories in the horizontal (zx) plane, which is the non-bending pl?ne of the central detector dipole magnet and its compensating magnet downstream, (The coordinate frame i£ a ri yht.- handed system with x parallel to the incident proton direction and y verti cally upward. The origin is at the beam crossing point}. Figures 5 and 6 show 40 kaon and proton trajectories in the bending (yx) plane. Whereas muons were traced through the forward detector out to x of 12 meters» had- rons were terminated upon striking a calorimeter. Figures 7 through 10 show single Ag decays with all particles tracked out to x of 12 meters. The geometric acceptance of the detector for Ag •+ y{\i u~)K~p was computed at 50% for production at x ~ 0.3-0.9. The criterion for acceptance was that all 4 tracks should traverse at least 1 meter of drift chamber. - 198 - References 1. K. L. Giboni et al., Phys. Lett. 85B (1979) 437; w. Lockman et al., Phys. Lett. 85B (1979) 443; D. Drijard et al., Phys. Lett. 85B (1979) 452. 2. A. Astbury et al., "A 4TI Solid Angle Detector for the SPS Used as a Proton-Antiproton Collider at a Center of Mass Energy of 540 GeV", CERN/SPSC/78-06, SPSC/P92. 3. H. Fritzsch, "How to Oiscover the b Flavored Baryons", University of Bern preprint, Nov. 1979, see also H. Fritisch, Phys. Lett. 86B (1979) 343. 4. See for example, A. Kernan, Proceedings of the 1979 International Symposium on Lepton and Photon Interactions at High Energies, Fermilab, Aug. 1979, p. 535. PL(GeV/c Fig. 1 . pT versus p. for the decay products of AB(5.7) -> V K P, •* •» ^\.~. Distributions are shown for /.& produced with p-^o and Feynman x of 0.3 and 0.9. 0 20 40 60 BO 0 20 40 60 SO 100 120 140 PL(GeV/c) Fig. 2. p, distributions for the decay products of/!B(5.7) » f K" p, Y * n v~ • EM CALORIMETER VERY FORWARD ENOCAP / CALCOM CHAMBER CALORIMETER CHAMBER 14 ROME I . \ .CHAMBE.CHAMBER I Orii la=g=iltl•£31 £t m J COMPENSATOR MAGNET CALORIMETER I J_ _l_ _1_ _L _1_ _L 8 10 14 X (METERS) Fig. 3. Vertical section of the "Forward Arm" of the UAl detector. 40 MUONS X(A ) 0.4 B =0.3 0.2 r*^r- 0 -0.2 £ -0.4 r- _J_ J_ Ul 40 MUONS X(A„) = 0.9 2 0.4 N 0.2 0 -0.2 ~£M~~?^£*klW- -0.4 CENTRAL J_ _L _L- 2 4 6 8 10 12 X(METERS) Fig. 4. Trajectories in the hori2ontal plane of muons from the decay sequence AB(b.7j - T K"p, * • \j u~ ; AB has Feynman x of 0.3 and 0.9. 40 KAONS •—•—• • • • 4 6 8 X (METERS) Fig. 5. Trajectories in the vertical plane of kaons from the decay AB(5.7) * H' K"p; AB has Feynman x of 0.3 and 0.9. 40 PROTONS X(A ) =0.3 0.4 B < m • t 9 0.2 0 .'••••••»•• -0.2 • •* • *• .» ce -0.4 _1_ _1_ 40 PROTONS X(A ) = 0.9 0.4 B DRIFT 0.2 CHAMBERS BEAM PIPE 0 "y"'"""*'" = ll = * = ggL'" • • •" V "• t -0.2 CALCOM ENOCAP • • • I • CENTRAL 0.4 J L X(METERS) Fig. 6. Trajectories in th« vertical plane of proton from the decay A„(5.7) • 4' K"p; A„ has Feynman x of 0.3 and 0.9. X ( AB) = 0 3 0.5 .--'H-* CO ce LU /^- r- LU -0.5 Af- 05 CO cc LU r- LU 0 • • > > » # • » « ENDCAP CALCOM ^ > CENTRAUX ROME -0.5 -Lia L X 4 6 8 10 14 X (METERS) Fig. 7. Horizontal and vertical projections of the decay products of AB(5.7) * V K"p, f » uV, for x(AB) of 0.3. x ( AB) = 0.3 05 CO ce -'' ———-——-~~~p LU r- o- <^c LU - <^zr~~ K" "•** -0.5 I i 1 1 1 1 1 0.5 o: LU ••JJU^lC F" . -i- i J- 2 ENDCAP CALCOM ^ CENTRAL -s -0.5 1 1 1 1 1^1 1 4 6 8 10 12 X(METERS) Horizontal and vertical projections of the decay products of Fig. B. AB(5.7) - ï K"p, * - uV, for x(AB) of 0.3. /(AB) = 0 9 05 - (f) _P CE ~ LU ••K" H 0 - « UJ 11 ^ "M" M 0 ^ 05 a: •M" LU .p ENDCAP CALCOM F* CENTRAL ROME -05 4 6 8 12 X(METERS) Fig. 9. Horizontal and vertical projection of the decay products of ;.B(5.7) - 1 K"p, • - uV for x(AB) of 0.9. 0.5- CE Ld ENDCAP CALCOM P > CENTRAL RO^TE -05- _±_ 6 8 10 12 14 X (METERS) Horizontal and vertical projection of the decay products of Fig. 10. A„(5.7) - Y K~p, t •- yV for x(Ao) of 0.9. Pbnr-P I-'A-l co) Inborn t ion Pub. H TN IIU/tM Apn 1 21 , l!)i!(l W.fi. Srol I. - 209 - I'-wl kip id nut i r i r ^ I inn using tlK/rix 1 ) I n 1 rodnr I i on In a ny i nvcs I i gn '. i on involving new pa r t i c I e s eg : h nn vy qua rk ri;ivotns I), t. etc. il. snems nui In lihrjy Dial pari icli! i (1 en I. i r i r.a I i on , l>;i r1 i i:u 1 a r I y s L ran go par L i r. I e identification, will play an impor Inn t. role. In I M i s eon Ir i bu I i on wn out J inn so nm I h rom L i r;i I en 1 eu 1 a I i on s performed at {'FUN which are a it.Td primarily ill. accessing I he n s [• I'u 1 nés s of <( K/dx i den t i f i en t i on in I ho IIA 1 ( pp) cnnlrnl d e Lee lor- .""• 2 ) The ore t i ca I r-'ilrnl a I i nn : A theoretical rn I eu I ;i L i on of the nnrrgy loss d i s t r i bu t i on of a charged particle in a sample of gas requires l.he energy loss cross- see I i on per ijns mo Irculn div'dl! . ( Ii is the energy 1 os t by the eh a rged pa r1, t c 1 e K 'I'h is is obtained by integrating the double differential cros's-srn I i on d MJ/'dlMQ over !\ i noma Lienlly accessible inoini'n Linn transfers (J. (more precisely Q is defined as the corresponding energy Iransfrr if the collision were assumed to occur from a free e1RCIron ) . The double differenLia I cross-section can be written in terms of the distribution of electronic oscillator strength s Irenglh along t ht; real pho ton line d f /d IÎ | r <• » i photon while at 1 arnn moine n t uni transfers (Q~> *=K . V,. of the n 1 re 1 ron s in the a torn ) the effect of Ihe atomic binding can be neglected and all the oscillator strength accumulates close to the free electron line Q = li. As a first approximation the distribution of oscillator strength on the Q,R plane is given by the expression1' : E df/dt:(K,0) = d r/dK | r« • i photon 4 / dr/dlï|re . i photon !.b.H> :;;ilsifiRS Ibn Bcl.he sum-ruin2» for nil Q if it is sal. isf ird Tor rr;i 1 phn t ons . Pho I o.ibsorpl, i on cross-snn I, i on Tor Argon3 > and Tor e thane arc shown in K i g. I. Phot on bsorp I. i on rross-scrtions i"or methane, propane and bn I aim am also available from He f . 11 . The so en 1 ' cd density effect is incerimrnlcd i ti the calculation h.v modifying t.bn pbolon propagator in I hi! expression for the cros s s ee I i on to account Tor absorption and d i s pe r s i on in the gaseous medium, before performing the i n I egra I i on over- (J. The final expression for the differential energy los.v rross-sre I i on per gas mo I entile heroines : t\,j '(li: = n/ '{T.I<* ) . idr» /lO . [ ln(2m/I2/K)4( 1 117* -fl2 Ï e f T ] + ( tflirri' ••'<>'„ = (\/V.).f (Tr dK, L'S = pho toabsoi p t i on cross-section and (Iin?-/i?»err=l/(1+î:i2 + r2?^n[(l-/ï2+f:i/ï2)z+/f-1rz;:]-i/z J-O^-M+Ï i )/<(1+EI >*+rz* ))lan-i[j8ïKî/(l-^ + i:i/l! ) j f i and i. * nr,: the real and imaginary parts of the dielectric ronstanl given by : o(K> = N^, (!•:)/!•: EI(R) = (2/ir) / i:?(li' ) B'/( li ' »-E* )dE ' and ,\' is the density in gas mol cnul cs/uni t. volume. The hnndau il i s t r i t>u lion for a finite sample length is obtained from the one r gy loss cross-section per gas molecule by repented convolutions starting from a thin sample. The energy loss cross-section (1) and the convolution procedure have been coded in Fortran and details of Ihe program are given elsewhere ( f> ) . It may be of interest to remark here that (from eq. (\)) the mean energy 1ossnd by the ehn rged part i c1e/ems d K/dx, the moan number of col I isions/i:ins dN/dx, and the real pnrt of the static d i e I c n t r i c constant. /. i((t) ure essentially proportional to suceossivn moments oT t h e p li o 1.1) absorption i: r o s s - s e c t i o n : r. i((l) n /ira/li*f!R Pbar-l* HA- J collaboration Pub. H TN Ull/O-l Apn 1 21 , 10111) ,. . W.G. Sco I t. While the mean energy loss is essentially guaranteed to be rorront in Ihr model provided I ha t Ihr. input photoabsorption nross-ser.l. ion obeys t (II> siiin-niic, l h n higher mom on t. s are i nr.r on singly srn.vi livo 11> the exact 'I i s I i- i bu I i on of Itin 1 ow lying osr i 1 I n tor s trnngl li. Thus the com pa v i son of the computed dielectric constant with tabulated vnlurs obtained from low frequency re.frnolivo index men su rninnn t s ( !•'i g . It) s re ve s as a check on I he i npu L pho Loabsorpt i on e ro>; s- se c I. i on s . As (Imcusscd below it turns out that for sample lenglhs about 1 a t in. cms. Min mean mini her of collisions/ems < 'J i (lomna r i snn w i I h n.vnnr imrn I l-'igure :i shows a preliminary data for the I.nndau distribution for 1 (icV/'r x- in •.'• II.tin (-ins slice of Argon lid"; ethane obtained using the 20 ems d v i f t. chamber a I CHUN . The one rsiy sea le in KeV ha s been calibrated using the Argon escape peak (2.05 KnV) oxciled using an Ke^ sdiirre. The data linvo born corroded For the. effects of inler than lie 1 cross- t a I k . The rurve is a t hrorn I i en I prediction based on Mie procedure out ) t ned a hove . F i g. *1 shows a similar plot for I V, r?V/r. electrons. While I lie model predicts correctly Ihe pion data which are close to the mi n iiiium i on i 7 i ng there is a t (Mid enr.y to ovcrr.s t i ma t e the effect of the relativistic rise. This problem is not understood at preset! I . •1 ) IVed i el ions of the model tl'r assume no1*' that the Minore I, i ca 1 model discussed in section l« dors enable us Lo prod i eI norrocIly the Landau d i sIr i bnI i on Tor a g i vi* M s ami) I e length of gas . Star t i ng at this point it i s e I i-a r ly a simple matter to predict the distribution of any chosen i on i zn I. i on estimator obtained by repeated sampling of individual tracks. As an ex amp I e wn show as a function of inomcn turn in Ki g. *1 the predicted mean jouirai ion loss of the lowesl 00" of IDC) X 1 ems samp I es for the s tandard argon 00" ethane mixture. Since the d i s i ri lui t i on of this mean is expected to be closely gauss i an wc also show the ± i n lines rompu ted from the rins of the d i s tr i bu t i on of the means. Note that while separate curvns am given for IT, K, and p, as Pbar-P UA-1 col Inborn t ion Pub. // TN BU/lM Apr i ! ïi. ÎÎMU1 W.tî. Srol t c:iii br- SIM:I\ from cq. (t) the result is in fact, a function of 7;? only .nid the different (îui-vrs are rr ) n I ne) by a l in 11 s 1 n t 1 011 n 1 on y Mit; I oya r 1 t hmi c momen t. uni nxis, Fig- ^ m"! Fia. f> show similar curves for arc on ;i lui el liane sr pa rn I cl y . Slarl.iny from curves 1 i U e Fig. 1 , T), fï wr can compute tht; expected e r f i c 1 enry of a pa r I i t:u l ;i r selection a I gor i 111111. liiven e s (. i nia I <> s for- Mu- n-lalivd particle y i cl il s nv'K/p wn can also compute the <:.\ pe c I cd purity of Ihe resulting sample. As nu example wn show as n function nf îiunii'-n I uni in Fi g. 7 the c l'f c c I of srlncling tracks which lie within ± l.r of the i!X|irf led idiiii'al ion for knons t n argon (>f)" l'I.hnnr assuming relative yields in Uni ratio ir/K/p - \\/\/{\/\\) . Clearly with this si- I ce t i on Ihe r f f i r. i enry for- knons is a bon t 70% i nd r pendent o f m oui en t mu wh i 1 e the con I am i ua t i on of pions IN Inss t.han aboul 10."' in ! lie acuité n t un range p = M-T> GeV/e rising to a bo 111. fil)" al p = 2 CpV/i: and [) = 1.1 CeV-'r. While in this example the eon lam i un t i on fr Tlii' above model presumably enables us to calculate precisely the particle separability for any chosen gas mixture, sample length, a I gor i I h m i'lr, II may help I o re mt; in be r h owe ver, as men I i oned i n section I t ha t for sample ! h i ekness es and pre usures a round 1 at m cms t he re la I i vi' wicl Mi (re la t i ve to the peak pos i t ion) of t lie peak of the Landau distribution (and hence the relative width of I he distribution of Mie Iruur.aled mean) is determined by the fluctuations in thn number o I pit ma i-y eo 1 I i s i ons . Coin pa re the rr so lui i on in Mit; i on i ;• a lion between argon and ethane Fig. ft and Fig. l> with the energy loss eross- SITIID!) Fig. H. The number of collisions in ethane is around •lU/eins in the ea^e of argon and around Hit/cms in the case of ethane and the resolution (expressed as a fraction of the truncated mean\ is corresponding!y better in ethane. As a practical example wn show the percentage improvement in partie In separability obtained by doubling the mint lier of samp les for a fixed track length as deduced by Va lent a '•1 a 1 . ,r- > . (The pa r t i e 1 e sépara bi 1 i ty is defined by the difference in Mie truncated means ( n~K)/v'nll\\ at momentum p = 3.0 GeV/n). The graph shows very clearly that for Pt about 1 atm.cms the improvement obtained by doubling the number of samples at fixed length is about :l--t" only. Note that for fixed length the total number- of primary collisions remains fixed, nil the improvement coming from the better Pbnr-P I1A-I collaboration Pub. îl TN HO/D-î Apri 1 21 , lOilH I IP;I I mini I of the "In ils" of Ihc l.nndnu d i s I r i bu I i on in the case of the 1 a r gr r niiinbe r of s ninp les. At fixed total I engt li ( eg. for a fixed number- of s;wnp I es u I fixed length) fin f* nan inrriMsc lite number of atomic i:«I] isions by i n erra s i n » t lir pressure o f gas , when the improvement in pnr U r I n se para b i 1 i ly is expeclrd l.o be propor 1. i ona 1 l.o Vprnssiirc. Fig. i) shows the inrnsurnl si'pn r;i I» i I i t y as a funclion of pressure for fixed lofa I length In km from Ilef. li ) . Tin* particle sn pa ra b i I i \y is n Vprnssun: for pressures less than a bo ul Cal mo s pherrs. Finally we nolo thai for all gases the particle separability is limited ;il. high women t u in due to Lhr density ofroel. Comparing Figs. r> and f» for cvawp) J: we OIISITVI; thai a 1 though t he ri'tn t u I i "h i n ioni/al.ion is considerably better in ethane l.i.an in argon I.lie ousel of the diinsi Ly crfccl is more rapid in ethane than in argon and the pa r I i r I r m-i'ii ra h i ( i i v as a function of momentum in the two gases (urns ou t to be vi' y y similar-. A 1 I hough this fciihirr is prrd i c 1 ed b}' I he délai 1 ed en I en I a I i on (section 1 ) , the d t s (.r i bu t i on of oscillator strength enters in a eomp I i r.n L ed way (via the rrfrnrtive indices) in the f o nnu la for the rross-scri i on ( oq . 1 ) . Fo r this mas on i t. h a s n o I so far proved possible to analyse in a simple way how lo choose the • >srillntor st.rmgl.Ii so as lo minimize the density effect in the interesting moine » I urn range while at the same time keeping the number of primary collisions as large as possible in order Lo maximize the par ( i c I e se pa ra b i i i l y . F i g . ID ( aga i u I a ken from Jtof . (ï ) s ho if s Die maximum momentum for- useful particle identifiration (as defined in It of. li) plotted versus pressure for different gas os. It 1 Summary l.i e t a i I i>d ea 1 eu 1 a t i on s show that efficient chn rgod particle i (ten t i f i ea t ion by dK/dx is i n pr i ne i p te poss i b 1 e î n n I imi Led women lui» l'iinyi' in the HAÏ central detector as now envisaged. The technique is likely l.o hi: most, useful for iden t i fy i ng knons in the mom en turn range p = Z - ir> (ifiV/n. In considering particle identification by d li/'dx it is useful lo bear in mind that for sample lengths about 1 aim.em? the re I a I i ve width of the peak of the Landau d i s tr i bu t i on (and hence the relalive width of the distribution of the mean ionization) is ess m tin) ) y de I i-rmi nod by nnmbrr. of primary ionizing collisions. It does not seem lo be possible to understand the precise effect of the ousel of the density effect without recourse l.o tlrln i I rd ( cotnpu 1er) calculât ions. Pbar-P UA-1 roi laboralion Pub. H TN 8(1/(11 Apri I g( , mill) W.n. Sr.oU ' 1 II v f c r n n y p s 11 tf.ïl.M. Allison unci .1 . H. Cobb Oxford Univ. preprint. Kl/80. 2> Sri: for example U. Kaiio liev. Nucl. Science V.I3 (l!)(î;i). :i> J.A.Ii. Sampson Aclv.Atm.Mol .Phys. V.2 (ÎOBH) 178. •Il [1.1. Rchoeii. J. Clicin, l'bys. V.31 (IBB2) 2032. f) l W. C . Scott, For-t-hcoîiii ng pp UAl note. (il A.H. Valentn et al.. Nue I . Inslr.Mo th. IG1 (1070) .15. Pbar-P UA-1 collaboration Pub. It TN HO/ni ApriI Z\ . IflHU 11) Pi iMiri1 r a n t. i o n s : !) Photo-absorption coefficients for argon nnd ethane at oTr plottnd vnrsiis photon energy. 2) The r«frarUvn indices for argon and ethane plotted versus energy computed from I he photo-absorption cross-seetions. The crosses represent some available refractive wide* mensnrrments. '\) Measured Landau distribution for ] UoV/c IT- in O.fl.'i cms of Argon till": ethane mixture. The curve is the theoretical prediction. ») As for Kig. J but for 1 GeV/c c". fj ) The pred i r t ed d i s tr i but i on of the trunea I ed mean (mean of the 1 owes I fid" ) for pious, knons and pro Lous p I ot ted versus momen I inn, M sstimi ng I (K) x I ems samples of Argon 00?; c thane mix lure. The curves represent ± 1 a contours. l> i As for Fig. 0 but. for pure Argon. 7) As for Kig. f> but for pure Ethane. t\) P.f f cr. L of ± I o selection for kaon (broken curves > assuming 100 x 1 cms .samples of Argon nor: eLhane. The solid curve shows the initial m tes assumed 0) The energy loss cross-section per gas molecule for 1 (icV/c pions plotted versus energy loss for Argon and ethane. 10) Pc re en I age i mprovemen t in par t i c1e sépara L i on obi a i nnd by doubling the number of samples for fixed detector length for various gases p I ot tod versus pressure x samp le length. ( Pi gum eopi ed from lief . 15 > . 11) Pi on-kaon se pa rnt i on plotted versus pressure and number of samp 1 es for- f t xv. d total length ( P i gure eopi ed from Re f . 6) . 12) Momen I inn limit for particle identification plotted versus pressure for various gases . ( Pi gurc copi ed from ïïof . li ) . Absorption coefficient (cms-1) o o o o o 1 1 1 1 1 ll|| 1" 1 1 M' 1 1 11 1 1 1 1 1 M i | - Ionizatio n _ DISCRETE TRCMqrru-mq y _ threshol d *> - V - m < ^ Ul - - Argo n V Argo n idg e en 1 i ffiiil 1 1 1 1 1 1 1 il 1 1 1 1 1 1 M 1 i i i iiini i i i i 11 M i 1 Ml ill - Ionizatio n r threshol d 3 .& - " m S: Ol Eth a ?S 3 - ^^ & 1 CD - *^ CD ~* i "f i 1 1 1 1 1 1 1 il 1 1 III III 1 1 1 1 ' 1 1 l 1 i 1 i ï r Predicted refractive indices compared to Expt, 3000- o ^vEthane -ï 2000 - - /Argon / l / X ~ / • / 1000-- X — "~ "" % 1 1 1 l 1 l 1 i 1 1 1 1 1 1 2 4 6 8 10 12 14 16 Ey(eV) •L -i—•—i—'—r -i—i—r E T E 'J Fig. 3 -i : 1 •• i < 1 > r 0-83 cw^s flvojoi^ CÛ% e.'Hvoiw.t EIIG'V LOSI'IN KÉU" " FiR. 4 r fig. 5 > 1 1 SO '•— — -—'--———.-—'.—: :: - - - ••- — : - -;--~ —,— — .._ __—.—, ,.,.- — \\ \ i W • : \ ' ' \ \ il \\-—\\ : :-:" ...... :.-- - ... - -|\ -• ;--\|-—U ; ;••-- -_-..-_. —.: . - --U--; -\-H"A\ " ~ • •-- H— —--••- -UK—: \vf<-- -Up—' -——- — - --...--^-,- -, •- -• \\ \i • U f U \i • \\ - U „—Vv~~-\\ -• ^--—: :—^^^=~-~~~Z^^^^^^ - \\ ' • \\ • \\ .;••••: .^. 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Ill 1 1 1 1 1 II ll /« 1*0 |uoo ~i 1—i 1—i—I 1—! 1—1 > 1 r Energy loss cross-section per molecule > 5 • Argon~40 events /cms 4 cms " • Ethane ~ 80 events/cms —LU- 3 b T3 j- -L —i 1 0 20 40 60 80 100 120 E (eV) Fie- 9 • p/ef«n<. * &}t\QI* - // / Ay —J— • J© fie. 10 o e fie, u Joy fx«st (%f*.( (w- 38M (WsifS.VuO 21* 1 0.1 to too Pc*M C I* r Fig. 12 X^wT(fttw\»«J te KMcnoiJ op |o»r i -i-ir Q^^ip&'Ae). le ••» 100 PCk - 229 - b-FLAVOUR PRODUCTION IN THE FORWARD ARM OF THE UA1 EXPERIMENT F Hippo Ceradini Istituto Nazionale di Fisica Nucleare - Sezione di Roma Recent experiment at the CERN ISR have measured with solid statistics the forward production of strange baryons1 ' 2 and shown evidence for the production of the lowest state of the charmed baryon family (A +„1 3 4.5 .On the basis of these data the expected cross section for b flavoured par ticles and the acceptance for a restricted set of decay modes involving J/f and V°'s production in the framework of the UA1 experiment at the CERN pp Collider can be infer red. 1. - b-flavour production in the forward region - Transparency 1, T1, shows an oversimplified picture of the diftractive excitation of a proton into a bb pair: pp •* leading system (p + pions) + ... b-baryon + b-meson + pions With this naive approach the cross section for bb pro duction can be expressed as o . r = o • kinematic factor (m, , s) • bb 2b (2) form factor (m., o(pp •*• bx) • BR • ACCEPTANCE • EFFICIENCY -iA-32 2 2. - Decay modes and branching fractions - T3 and T4 show the amplitude for the decay of the b-quark into different final states as derived from Ref.8. In particular T4 provides a brief Michelin guide for the experimentalist (suppression sine squared are underlined). See Ref. 9 for a more original contribution. Disregarding the semileptonic decays involving neutrinos, the most appealing hadronic decay mode is b + ces with a branching fraction of < 10%. Among all possible ways the c,c,s quarks can dress themselves into hadrons, when the cc pair makes up a V (about 50% of the cases following Ref. 9) a strong signature is offered to the experimenta list: v identification (and in case f trigger) + stran ge particle. In T4 B is the lowest b-flavoured meson (B+ = ub> and A? is the lowest baryon (A £ = udb). 3. - Signature and detection of b-flavoured particles in the UM forward arm - In the following I will considère the possibility of detecting decay modes of A°b and B- in the forward arm of the UA1 experiment, i.e. the highest rapidity region of the Central Detector Forward Chamber (y> 3), the End Cap, the Calcomp and the Very Forward chambers. T5 contains a summary of shorthand calculation for the momentum resolution in the different UA1 forward detectors (see Refs. 10 and 11 for more details). Units are GeV/c, T, m; o and &y' are the coordinate and angle resolutions in the drift plane. A.Kernan presented Monte Carlo results on the decay mode A £ + V K"p 12 but from T10 and Ref. 13 appears that it is extremely hard to identify high momentum kaons in the forward chambers by exploiting the dE/dx measurement. I will treat the detection of V°'s ( A ° + V A° j B- •*• T K° IT -) on the basis of simple criteria for the V° signature. For the detection of If via the f -*• u u" decay mode see Ref. 14. T6 shows a two projection picture of a typical A £ + ¥ A0-*- u+ u" p IT" decayi+) (up = bending = drift plane. I'm indebted to A.Kernan for giving me a set of Au-* fA pictures. - 232 - down = non bending = charge division plane). In the picture the dark lines represent the beam pipe and the light lines delimitate the chambers. Central Detector, End Cap, Calcomp, Very Forward moving from right to left. T7 and T8 contain the criteria for the V° identification. It appears that these criteria are somehow in conflict, i.e. the parent particle of the V° can't be too slow in order to reconstruct the secondary vertex outside the interaction region, assumed to be + 0.3 m along the beam axis, and can't be too fast in order to have enough lever arm to measure the momenta in the Central Detector Forward Chamber. Emission angles as well are bounded not to be too small or too large. As a result the * will be slightly boosted forward still leaving a lar ge window in the two body phase space, but the Dalitz plot will not be evenly populated. As an exercise the two body decay modes A O ^. Ï AO+ y+ p- p ïï" + B± , * K±*- y g" K° *± have been studied by adapting the Monte Carlo program of Ref. 10 to a CAVIAR processor. The following table gives a summary (see T9): decay particle mass model for the accepted fraction (GeV/c^) cross section of events JlJ-f a" 5.7 (1-Xp)exp(-2.5pT ) 15* 3 B -• V K* 5.3 (1-Xp) exp(-2.5pT ) 25% No cuts have been applied to the muons. In the decay involving A°, as additional requirement, the proton should be identified as not being a TT in the End Cap chamber (see T10) . The other trasparencies show distributions of polar angle angles and momenta for the A . -* VA0 decay mode: T11 : polar angle of either muon, 0 T12 ; momentum of either muan, p T13 : polar angle of the proton 0 * with the accepted region T14 : momentum of the proton, p f with the accepted region T15 : polar angle of the pion , 0 , with the accepted region T16 : momentum of the pion T17 : polar angle of the A°, Qh , with the accepted region T18 : momentum of the A , p , with the accepted region 4. - Possible trigger schemes (T19, T20) - No attempt has been done toevaluate by Monte Carlo possi ble trigger efficiencies since this is a many body problem, but from the experience at the 1SR a few ideas can be put together. Among the trigger schemes used in Refs-3,4,5 the explicit diffractive is hard in UA1 since only a frac tion of a percent of the quasi elastic (anti) proton will not escape inside the beam pipe 1 5, a single arm inclusive trigger may suffer a too high beam gas background. A com promise could be to ask for a very low or very high frac tion of the longitudinal momentum (i.e. calorimeter energy) in the opposit emisphere in coincidence with a high mass system emitted at relatively high Xp in the b-particle emi sphere i large longitudinal momentum (i.e. calorimeter ener gy) combined with relatively large transverse energy or re latively large opening angles and/or high multiplicity. The trigger processor for the UA1 experiment can pro vide the most convenient trigger using the information from the 4 quadrants of the Very Forward calorimeter, the 8 octants of the Calcomp and the sectors of the I's of both arms. I would like to thank Anne Kernan and Giorgio Salvini for illuminating discussions and Roberto Bonino for writing the program on the CAVIAR processor. ( - 235 - - References - 1 S.Erhan et al., Phys. Lett. £5B, 447 (1979). 2 M.M.Block et al.,CERN-EP/19-82, contribution to the EPS Conference on High Energy Physics, Geneva, June 1979. H.Sens: contribution to this Workshop. 3 K.L.Giboni et al., Phys. Lett. 85B, 437 (1979). 4 W.Lockman et al., Phys. Lett. J35B, 443 (1979). 5 D.Drijard et al., Phys. Lett. B5B, 4-.-.: (1979). 6 C.Peterson: contribution to this Workshop. 7 G.Gustafson, C.Peterson, Phys. Lett. 67B, B1 (1977). 8 N.Cabibbo, L.Maiani, Phys. Lett. 87B, 366 (1979). 9 H.Fritzsch: contribution to this Workshop. 10 F.Ceradini, F.Lacava: 0A1 internal note TN 58. 11 M.J.Corden, H.Eichinger, A.Norton: UA1 internal note TN 60. 12 A.Kernan: contribution to this Workshop. 13 W.Scott: contribution to this Workshop. 14 C.Qhesquiere: contribution to this Workshop. T.Hansl: contribution to this Workshop. 15 From the Monte Carlo of Ref. 10 using as invariant cross section (s/it )d2«r /dM2dt ~exp (6t) /K2 extrapolated from the data of M.G.Albrow et al., Nucl. Phys. B108, 1 (1976). 16 M.J.Cawthraw,G.M.Mcpherson, D.N.Wilson: UA1 internal note TM 79.44. 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VF -lU/Wi + 8 F iuJtorx •+ eutu>W«lAw J»0itcAo 0*4***) i kua. tU uuiXty^ty, trwuw* *-(u^y, 2 p. «-cyUv»«ui*ati ivc t^itr fro lu>l Pl> UA-1 collaboration May H7 . 1 !)H(l Til H JsMiON njnjyjTJiLll AN.U nA(:KClt I 1 I n I rodur I. i on Add i t i on ïi I ;/-d i'I cr I ors in the forward rrsgion uT the UA I drloclor. f . e . fo I I ow i ng I lie CAI.COM or/and t ho Roman Caloritnntrr \rv. of iiilcrpsl for sr t'r ra i rea sons - New /f- pli.vs i c. s i i) forward (I i rcr. t i on (din nn prodtir. t i on . ;* bund 1 rs ) V.x I 'Mis i on ?a<:or 1 ap of the presently forrsrrn //-de If c I or by a ilclrriiir I lia t sers large r Tap i d i I y valurs. Of the ipirsl ions It) be Miiswrrn! : i ) I r i »gf |- on ind-rrsl ing events. \\\ liar Njt, (unid In I lii s Iriggrr. i\\) reduction of this l>n ok ground , i v * me ii s n r fin en t. iicrurnry , we will lrr.il i i ) and i i i "t i n tli i s note . The nniju 1 n r régi on lo be discussed is il < 15°, wh i r.h enn be d i v ided info sever a I ;:ones A , Il, (*, acronl i ng to the « ovum go by I he KNU-CAT, ("At,COM a nd I lie union chain be rs , see Fig. 1 . The angular regi oils are suniMiii r i sed i n Tali lei. £> Assumptions for MC background génération For I lir f (i 1 I ow i ng we will assume I if "-V- 1 I-«I liilmrn I inn - J58 - lir'n.'si'r rni. fill inluirti . AI per . I :i I I i I I i n I i i- i I '. AN = :l.r, '.V i I r-rnls nrr i>ivrn ill K i G. '.'. rind t VI i; . : ill liny physics in f Ctrl,'.'» r .i (lin-r-l icii »l]l l,r in r.M.r.'M is liiljlirl- by n larlnr "I" nl..ml :.'ll lli.il .. I .Inns 1 I ' In- inns I rrm.d.-d rrnioil -'\4|- M'i'li I.'. rhril Kl-nnl Vi I i'1 ni-I ni . 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Kvrn in t lm wors t. rase ( I (ln ) punch t h rough is less Hi an dim ay by a far I or- of 25. For f>n tlm dnnay pa I.h is about H m, for in, bu I Tor fixed Pt ibis factor is compensated btmausc y (2 . Tin ) = 27 ( r>n ) , The; dim. a y con t r i bu 1 i on at 1 (>o is a factor of Z hid her Ih'in I. hi) one a I r>", again dun to I he 7 factors. 1111 era 1:1 » ons con t r i hu I c- to Mm background , who 11 I hey occur within a distance 1(10 from the outer surface of thn material, where MR) is growi ng I ogn r i f htn i ra I I y with K, Pig. 5 . A t raciV Vf i lit Figure fib) shows the background inlogrnted over all angles or all Pi vnliiRS, Tab I c. II summnr i ses the rates. II is clear from these numbers thai oven a 2-track trigger is not fensible in forward direction. 4 ) Hack ground rednet i on We discuss now po s s i b i 1 i t i e s to reduce this hi g h ra le : il) Add i t i mm ) i r - 3 - TN lui I) I PP U\- 1 co I 1 ;i born I i on TU H Kl1. - 2M) - - :.', V ;iv rcprcsriilnl ivp. Hfincr llic !>:> ol< cr<>un tc/>> ';>/<• i>\ I In- CAl.Cf'M (j>.<*:j ma> will slny I he snini'. IMI( ..I I nii;i ( «• I ••• ;i (;;i[» of .'1(1 CM JKIS lo lm left I'TPI1 aronml Uif* CAI.i'^M for 1 J <:h I ijui'lrs ainl 1 !.' ' s - > . V i g s . ? ,\ ) n ml ?b ^ show U) r siinu- i,-.i1(.n r-t Mir CAl.C'J",! is uni rovnrnl hy Mir muon dMrdor iliole of .il.! i , :: ,\ i .:.' m-1 > . |. i l''v-l ,!.•! i.nniMjil i.Mj or Hie IriwJi dl-OLL-JJili] • Tin* fnsl I ri<;.".er n s l..|.-.-.|, |.-t lii.- \:lr'I,r-,i Nino It - /' 1) ii»\ !>(' r S n r r I' J» I S ll-iW'|.'*î thilt po Mil l-ni'k l#. I1,i- "I'l-N". \> i ( li MI -i fcrt.irti .-tftfinlnr KIIHIIHV ^K , The limrs ) n vo I ••c 1 ri csi-r 1 r il-in T 1 s 1 1 i- v i- 1 :_'nil li'-i-l lin iiiiinl : Hill mind . . . Cf., mi ;,'l 1 111,1- ll«l- .II-,-I-|.| ii h li- C f i-i| Il i- Il r-.v 1 ,,i 1 " .Ir-.ï.l 1 mi- no di'iiil 1 inw- 1 no set- . .. Tl.r .,:,i'll|:,l ;, r i I-p I II I, i'I' lll.lt is W y, Il 1.1- (I f O I' Mil- foiW.1|''l Hill! 111.',.,' I) C i"H in.i I IMI ;,s |i,|l"„s, wlii'iT wi- nssinnr Ihnt muons lo l>f- nrrt-pl cil h.ivi- innmrn I II p ' ''il l.'l'V :'(•• : Tin- i" ilni- li> llu- inii'i-i Ininl.v of I lin vi-rli-i -(± lid c-in) is an I nil II-:I I 1 < 2f> inrnll . in l lioi i .-.on In I ) = II. '(•lu- »l ri 1 ir I ion in lin- mu «n 1' I i i- T i o 1 il (Cl) ï.l Ti-sln.m, CAl.COM J'okp M .-I Ti-sln .m) is lor Ir.irlis will) p '• 30 Hi-V/c : _Vi (VIT) v lui mi'iKl CAl.COM .volîl, rrfjinn. Jin (li(ir) ••• !if) inrnil i.UJj'.Ul JL!:iU_Li'.l_UJ.'J l m" X i mn I 110 X , ., ,, ) is Sinn I I . TN HM/(i:i |ip (IA-1 col I nliorn (. ion May £7, 1!IH(1 TUH-K1-; - 261 - un < 10 mrnd. One IhrirTom may choose i hn following nngnînr cuis for She two I r i Kli°'' ' eve Is |û«tf < inn mrnd 1st. level , | Art f < |l>fi mrnd 2nd Irve I . Kor the rejection of background from i u t era r t ions the lateral i^lnisioii of the shower is of little use as the d i s fan CM- I rorn I lie vertex (HI tn) is Nrgp (&n < ÎU mrnd >. The anguinr r. prend in I he sliowrr i about. HOI) mrnd) gives a reduction of ( An/TjOl) ) * . about 11.15 for 1st level, about tt.tll for and level . for hiM-kgi 'oiiiuf from d c r a y and lUinjih. i hr,ou«h an ftxnmp le of Hie accept nitre for different angular nils is listed in Ta b I e III. The nugn I »r eu t y i vrs a I. most, a reduct i on by n f ne lor 4 . The. re duc l i on Inrlnrs for d i I' 1er en I si^ns of the muon do ten t or hole are given in Table IV, the f i tut I trigger rales Aie listed in Tab in V. Kvcn w i i h an n ji.»n l,,a.r JHLL*HL'_LX R S^-LUUlX trigger is fraKible.- e) DisUiirr r>£ ! r i t;eer I r a r le s • An additional handle against ha rk ground from t nt erne ( i e-us is given by (he fact, that Z tracks from the snair shower arn ex pee let! to have a d i s I ait en of n bo» I A., = 10 (in i ton . The re«]u i r erne n I for a Z- t rack tr i gger r.ou Id therefore be I. h a I I hn t racks are at least in one projee I ion separated by *» v*2 A,. But this does not reduce (lie main b;i r U ground coming from f>1 Pisnission am! summary n ) A single /i- tr i gger in f or ward direction is not feasible. b) Mu on detection in forward i.t i iiiini'ini' r i in- -.ii 11' iii i ii lui-. |.i-i-ii |M . III.' Ii • • . II n h I i'i mi- HI ;'.l 'I I I I" i'i I'II Il I I,IMC ...i IT "I I I"' -Ml iJi i ii I •• !•!•. I'll I' ill i-.v I i-i.li i,n m-1 i. ii.(m i.i iii -|.. ii.i 11- H r i .'.' in \ I . .'' n-. ,il' I I ill... „ i I I, I Ii, Mm,II I'll I |>I I , i.-ip i il.i.ni .i : ni .-•. i ..ill, i h h I lii'si' VIIITII l'i mil i h'liiiln- Ml I,!' .1, I .1 ocs ( IN 11(1/(Kl pp UA-1 co I I nbarn I. i on Miiy 27. 11111(1 Til H/K H r - 263 - 2 ISO * t a a n n H ii ii s t ii H g H mi mm 11 ii i H ii » a n II n « t H » H H H H I H •gmi nsiut 03(1 cm (?) Il II II II II H H il H II » Il H H a H H t II II II II H II HU II HtM M 11 1 C* 11 g Ul o r i c n l n . i on 11 O . »r iibrs 1ola l nnmb (doi bin plnnc of lubes 1 .!>T> vert i n ii 6 2-1 r>.(if> (?) vnclica 25 1(10 a.-m h or i 7-on ni 2B 101 i. nr> hor i von ni •f I (?) (fil totn 1 :)!)2 I ti addition the s h i e ]<\ i ng n round the CAI.COM should be ns e 1 ose as poss i bl n to I he CA1.COM lo nllow for inorc thickness of this shielding without go i ng beyond UIP we i ghl al lowed l>y the CAIXOM s\ipi>or t ( hul : •1 Mem shielding close to the CAl.COM nrc loss effective than lOem al a d i s t juin e of HI) em ns desor i bed above ). Kor a second generation CAl.COM i'p ''*-1 '•*> 1 1 : • Mi'- til | i-ltl r-MlSt.i.T I'l rnl.'UfT' Ml tl CM.COM l-fl 1 'i| ||„.< t V [' I • i ', , l-.-i li-i --hi r III i i.r .ui.l '••• I I IT i-oii I r\ i min'i.1 "I 11 - >- -1 r ... I.-.- I ,-, '•H.'-v i » -\ i |..-i i-i ii i . -il inn ( i n~:> i :MII . .' > I T i • M -* r...,wn-ih | ( ., I | ..i, . -'. i;in--;«|H I I'I'C . I'M. i|..i i m-M,ii. i.. *;.'u'.i ti,i,. DiffBrcnl angular zones and Iheir coverage by different detector parts. The "fraction of tracks seen in a certain zone is calculated assuming a flat rapidity distribution. To get the absolute 0 of tracks/evenl a factor of nbout 60 has to be applied. covered by pspudo fraet ion free path rapid i ty of A(abs) for decay (degree) END CAP CALCOM ji-chambcr tracks Gcv/c (m) 0.7 •»• 1.3 portly 5.1 .-1.411 n 037 30 6.3 - 10. 1.3 - 3.3 fui ly »3.55 0 055 13 12.5 6.3 3.3 -» 4.7 partly ful ly add. /'C H »3. 10 0 021 6 3.0 - 6.3 4.7 -» 5.8 rul ly fui ly add. It CH 3. 19-2. SIB (i 013 21 3.0 5.» -»!! .2 fully partly add. CH .2.32 0 030 3.0 rully - Front 0 015 8.5 3.0 partly 14.4-»37.7 rully Front 2.07»1.07 0 U50 8.5 3.0 37.7-»90.0 in "C" - Top,Side »0.0 0 .0G3 > 5.4 1 .4 Bot torn TAI'.I j; i; Trai:ki .1i' t "r I <••! ilinhiT in] | " '. I ll (• Till- lihriinlli'r' is :,vsi|. 1 1 , c, IT II :'l «'.'I .'f 1 . I' 111': " ^-I'l.u" hull: .'ir-nui'l Mil' l-l'iii: ll].". Hi" I [1 |;iM'i' I :' ' i's II " y lit il I I Icr"!, I si-/1'. s or Mils [m ii'. I'i I III', .'T I' 1)1',I t'n '!{' into I |,f •il r ! (ml mil! I I ' i ) II-»/i . K —fi (li'im.v I HO') .lll'l ii) inli'ini-l Hill': i' I I h inn |-;,t I I I: I "s li.,1(1111', ill) I'uiirli lliioucli i s nrgl i a i I) I I' . II- i p.qcr pi oil 1 o u i •:(• Tri [ y IT /t-ch.itnlicr Ivntl dip II. 1 x 0 1 11.1 DIIL'Il i :inn II). II ^:'.I) :i i -i + 0 1 {!!>»! 1 . S x 1 . ;.' !).r, :IU':II) li'.KI - .11 1 111 '•i ::." 2 .11 s 2 .Il ? . 0 ;;t:i~> r, Hi ll. :i I:III ?fi 1-IKl Clip (1.1 x 0.1 ii.i in II !>*'«> II .11 :;i;n ;.'in + C.1 I ( mil l . •'. x i . :: 0 . li i'--..iu :i l ;-'. 1 mi * lllrm Fr a.o x 2.0 ? .0 i II:III lo l .10 Mine Id inn n r-. 1 J"i rvc n ^a «t ( Z; l r mi E^- *>l ! 1 ) ->.03S o.0*o . ' "' iJ.OAij ,'i71i O.O'îO 6.ÎSS S.12C 0.Î35 0,150 (f. 165 o.ino* (-.'»!;> t..*/-.. « O-tSi | 0 K*"*t* « iiti?S ft 0CJ30 Q.QhH P.0631 O.OéSï 0,0631 0,963i 0.0631 n,on3t 0.fi63t ,0 0 0.1356 0,135* '•« " '' " uys.i j P 1 1 Ah ;. M "5 U«2 P.I 1*13 ft.1332 0,1356 0,1356 0.1356 0,14(2 ••*.<<;i;;> * i-.*.: 0 13!H> o 1-lfi't (t tflSti 9.Î4*» Ç.S634 0.Î65H 0,1658 0.1658 fs.îfeMi 0.16^1 0.1715 V V.*i*»li c..|'.ys >.13} * . i n l '-: ii '.f,:7;' P ?j7-I n ?l*v.i n 3 2 «ST 0.3J« 0.37U (1,1011 0.4020 0.4fl52 0,4089 o.fliia 0.d4(ift s.. i S j «.Il6h •• /?':j <>?•.,, ! ii \?'st, ft l/3a (1.3834 0.42P-1 o.> ';, !l .11^7 o .1.1/fl «.3'"J S 0.flin3 0.4497 . Q.4797 0.4P51 0.4917 0.4V54 fi. & q a n O.^r-fiQ i, . 1 H J "» . 1 I't 1 ? .1 l; j.?2?h 0 131?/ Sit» 5770 0 M70 I,fi7'j0 0,7346 0.7782 0.7927 0,fl247 O.HJ4Û Ô.HJ72 I,hOOO ;*v;sv * " ftof background tracks accepted for different cuts on the angle difference between track and a straight connection to the origin « (o,o,o). The acceptance is given for different cuts in the two projected angles and for background from decay and punch through only. For interactions the acceptance is estimated to be (—-—r^—)*(—~—~-~-) . The detector set up is 40 cm Fe shielding around CALCOM Muon chamber of 4 x 4 ra2 , hole of 1.2 x 1.2 tn2 TAIII.E 1 Kril (1 I i "11 O f h:i f]. Fit Iriwks I'roin dncny or pniwli Hiroiiiih l]i: .irri.|.li'l rthrn Mi" h irl is r fill u I r pd I. O poinl 1.^1 r- linlli p I •' .1 f i ' I i-1' *- I'll'iili m :mrjr An . Thfi It'imbi-i * .1 i I I .M cul ':c|'i.iri- 111 • :i (if llii- ndil i I. ioiiii I union Mr I ill*- I 1 on o( b.-i r |. «t ..IIP-I I r.i' I • j nrni.pl i-.l »i I 1, i .-, I |,v < 1 (111 tnr nil i.v. 1- in-. „., , i n . I .\ I). I II. Ill ii . i. i (1.7 1 M . V) :.' . n \ ^ . I! 11.7 1 I! . 1 1! I ' . I v U.I 0 . 71.' (1 . '. 1 I ..-' .1 I . Ï (1. fill :'. n v ;:. it ll. r>? ii.:'.7 nil i il M nig Rales as defined in tnbtn 2), buI accepting only tracks with An I < i HO mrnd (tst level trigger), &a\ < Î05 mrad (2nd Nvel trigger). /i-de tec tor 1st 1 eve t tri gger 2nd level trigGer hoi e prol>. p Ï1 track Ï2trncks prob.p illr.ick J2tracl!!= *10» DCY 1 NT 1 1NT2 DCY*INT «10» DCY INT I I NTS IICYMNT End Cap 0.1 x 11.4 7.5 41)511 207 B 107 3.B 317(1 55 0.4 03 +Ca1 com l.Z x 1.2 5.2 2397 05 3 106 3.4 1615 25 0.2 21 2.(1 x 2.(1 5.4 111(10 02 3 31 3.4 1171 24 0.2 12 End Cap 0.4 x 0.4 5.7 3112 MO o.on on 4 .0 2215 id 0.4 41! +Ca 1 r. on 1.2 x i.2 3. 1 1100 5 n 20 1 .5 701 1 .4 (1 5 +add Fe 2.0 x 2.0 3.0 1030 2 0 10 1 .2 4 011 .4 0 2 Khi eld ing *• K f: "^ ,v,C a j M~C,'è ' ( 'J ''^O.^/, '.-| ^••.-."V_ S-p^,. ve^î^ > V V7 Vnr ~li—II—fl—II—i(""iTir x T i i î jiiiiiTii ill. ~i IN '- I'-- 't ^<-„(S \ooo \ loo i,:i7 •Lo (.Al.'c-t-i: -«- trw.o CAP ^*) 1 x 'W * ru J i—. \5l- -h'3 3s) 10, aSa/n'tkBro* •=• £ , -1) AO. \ 1_ ± ?, G<°\.'t Sfrât) to. ..^Hcpijw OF Cvfftrs "fiieyE. T}~ G. -- \[~T^^.~/7^rrz.Z& XA ( „.-... 1 ' • \ T^J/a _i .SAffu/e** febtjfê. __._ 2. top's 1 H&p dC ?fe) • ' • Tj._*•)_l _..^ ai- i,£.c/x ^Q 4k ?-f JJ^Z cJ-*s (pa. *-f \ \ |:> :,.,.. •-! i.... ' 1.1 II i •Lw. s '""J ; i™ •=: 3 <=:) £,-~.rc [,• <: .-.vw», ^ /,; . re -.; /- A kzu]) CAP -f CALCO^ I •""' '•& '" f\-ci<« { ' ,». -.f,h. 1 :aj - -if j. - _ a— „ i_a ••f Ï --4T I '* i n / p-..cJ. fc™-^:. I -!o- 0 i 1 GcV/c 2 6a^ Pir ~fij Go.) '&,Uy>-~-'t ^ f- ,(.ffr.i,,<-' -fyr*. cf h„c,?,^,.,L ••>••-< r-l;r*--f '-•"'> &• H^ •-'•> i'/wr-TiV^ r "i _T~ J-.tte^ch-i I ,/I- i L _r !"-• I I ,-'—r „ .'-.- ^ M - -'( to r -. „;..(;. i lc7L '.ItLCOy (.'uT^r^çf.oi? *Jl / f lo'- /l - Ao-i ! U4 I I i • -la'1 ^ <«V,-; ii'o-y.'-c WJ'T ..4 », ^J <\oL //o i r "i ••/»- /j..f ÎT3 7/,) -Ir, /;;. ,. 'J ti.j- CAP + OiLCon -t add. A-OH0.C sJ>-tC&*j ét^fjjt '» ,'e (ii**P"J-*r *f Aà- •b~ r "w I i .J i B-- "'*~ lap/ci. /1 9c +$ ) /)s /•J *^> Ù.f" /A. I. \ M - -J-HI- I I 1 J ! p Mss,..{-'f, >•;,.,. ni ..'PI ACfc li/inrffljff '('- 'JOt ) RI'/PiA-C HAH i i fSv STUDY OF A HUM FORWARD TRIGGKR IN UAl EXPKKIMENT C. GHE$QUlt:X£-t..l>.C.-Collège de i'nmc .«; detector of the UA1 experiment is completely . oVi-r^-d l>\ '.H-r* which span the angular ranges : 10° :;.<• l.S.R. have shown copious production of charmed parti' Its îrge values of X Feynïnan even in the diflractive region 1 X^C-3 ) i is to implenent che UAl equipment with what is necessary to i;.-n of particles with either charrr or Beauty (Truth ? l at tiu- I» X. t.i look where the decay particlc-s of such oh je vis run through ".; U" ii caractertstic signature could be usid to trigger the .u.i-v.ise the efficiency o£ detection. tiiilv we concentrate on a single production process : f p -> A. A + • • • ^ rK" .*t vxriude any other processes but give a more precise goal to the iriKHrr. : !f v.v have not considered the \i» -*• e*"e~ decay, because it ;.A u> the large conversion rate of a 's from ÏC* in the vacuum triym-r is quite hopeless with the actual set up. For the U. identification we have considered to use the actual calori meters ( ~f + hadronic) either CALCOM or Very Forward (VFC) to filter the hadrons and identify the JUL* S . (Fig. I). jut analysis. A Monte Carlo generation of events has been used, as reported in an earlier paper in this workshop (see A. Kernan's talk) corresponding to the production of AB at X = 0.3^pT = 0.0 GeV/c and X - 0.9; pT = 0.0 GeV/c. Out of the tracking of the u.' s through different parts of the detector we ran establish a classification of u. tracks according to the image chamber they see and what part of the filter (CALCOM or VFD) they cross, see Table I. From this table a very crude detection efficiency for a u. detected either behind the CALCOM or the VFC can be drawn ; Fig. 2. It shows 2 facts : - The overall efficiency for a single u. stays rather even for 0.3 - The detection behind the VFC in mandatory, from X ,> 0,3 the detection is predominantly behind the VFD. 1/ identification and trigger. The properties of the CALCOM and the VFC as filter could be resumed : CALCOM : 13.5 X . punch thru : 1.4 I0"5 abs 155 rad. length VFD : 8.8 À abL s 90 rad. length The projected scattering angle is ehown in fig. 3. nu r . .:, tt.-U'il l:\ the !.Ai.<:o;i i .mps ! r -.. . ,-• i . - i ;-. t. t'F!) fri'ir t.i : • >.ti fiiV. Thrc -.1 ii".:- "t irigijer li.-ivc been i:ons ideiv.l : É i - Ï.I..I îri^.iw : IndJcar inn ni" a jvli Lic;t- n.-r. :n. !" ---• . ; • l;P. Counter or .m <>K ,.;' [ ii. ;.-•...' :ï - '> 1 i ;^,'i ]• ; Chucking if the d i :..•. 1 i .•! liki-r ïs foDpiîL îbli' vit;. . M. i...... i i:.. licit- looked ttir (here p. ; 1 vU i - f'ilur iriser : Check it" the direction • •: ; 1. ...:. .-' behi m! Llu' l'i 1 UT is r,".ip..r .. ;. ' 1; . : . ..;'•.!: r...nwnliin» - of Llu- ûiei.Uîii 1 •• . To ;-r ••-',.: i i: ^:.if;es 2 and j v.v envi .-..ij.. :- . . ...-••.: tubes b t: s 1 i ' '. : .1. ::-li-rf. According te F" i j> . "J ;-,v :u .,-<. l. ::-.v\ , .,,:.i.'u:- -;• resolution .-;' ....: ni r;ui. ( 0S ac 80 GeV) . "litis cm .K ^;-.-Li ... . j-;.i;u. drift chamber villi 'J(H) tun precision separated by JO in. ;•. ilk this set up position .'f ', 1. ' t'.i«-k in the second plane with rfs;1»1--: t.- llu- i ir-u i •; .1 lution .11 : >. .-. .il I .Tin-; uncer Lainty and tht- .in^ulu <: ^ \t lu,- •'..•.- ;. -; . . oomentum of : :-. j-.u-j.irle crossing the magnetic liuj: .M LIU- I'AHÀ1'"., Vin. The Liiîv.: -•: m-:- M trigger need a prrrisc !i:,ih-'ii:i.. -. :' 1 ., 1 v.n r. ;:, t driit lri,:.'*r i> ciu-i .sinl t;u- incident traci; seen 1.' ik. i ;; u . of the till- 1. ïiiîs preiiaion could only be obtained .-titer .1 search of c.i within .T rt-st i-.:< ted pjrt of the image chamber bul vhrjv see. ; j J r.nuj i ^.Ui be found - in ttie forward region the particle density 1,- nirii - 111 .Ï .1 p-. tracking tl.ri; LU-- «..îjir.et isod CAUXKI. This means .; r.iU... ;• y , ,-..v ..:< ,-.;:..i probably off-li m-. Trigger sccmi». : VJe propose to pu i behind the CALCOM-Surroundin& tiu- Rome chamber- And behind the VI-'U, 4 phines of drift cubes, 2 horizontal, 2 verticil, st'p.'ir.ii ed by 20 cm. lli.^i mbi-b emild be similar to those used l • > r reiur.il u, IUU.-I.T (!50 x 45 TOT"). The CA1.COM eouid be covered by i x 1-'• tube.-;,J 11; l.*nn ,ind tlu VFC by 4 x (J lubes, I ,fc m long. A simple coincidence scheme (Fig. 5) could give an answer to the 2nd stage of trigger i.e.the slope of the trajectory in certain angular range within 2Z, 2 usee. The uncertainty on the position in the 2nd plane (Fig. 3) is taken into account by the adjustable width of the coincidence (80 A set of 92 coincidence units provide a one side detection of the u. 5 . In parallel the acquisition of the timing by DTR system provides the necessary accuracy at the stage of precise reconstruction. The use of 4 planes prevents the use of current division and increases the accuracy. U background. There are several sources of LC background, only a few sources have been looked at. 1 - Beam_gas__interaction_1 Li coming from the tunnel, either from beam gas interaction or any other proton lost in the machine, could be partially anticoincided at the fast stage by counters in front of the calorimeters (Fig. 1) as they cross both left and right forward arms . 2 - jL_and_K_deçay__in_flight± Assumption are 85 % 7t + 15 % K i i loo z u- e« i u < L decay > - 46.7 m/GeV. In CALCOM : In VFD : < E^ - 50 GeV Combining with the average number of 7C in. the rapidity range covered by the filters CALCOM AY - 1 1 u in CM.COM + IVLin VFD 9.51 Ivf* wiili Ail inli ut inelastic cross section. T spt-nJ t.) J |U 's in CAI.COM 10 ub 1 2 u. 's in VFD 5.8 ub 1 u in CAI.COM + 1 in VFD 38 Ltb VLiu:f sources of background. Thoy li;ive not been evaluated - Urell-Vann pairs - processes j l —> M*"M- - other vector meson decays p , d) ••- How does this background compare to J\ cross section fur instance A rouuli evaluation gives CT £w-^- &.-^-^ 0 jbppretil" or ^"~t0r ^ Âo production - taken as 70 u b • t £*) Reduction to a certain X range - COO ~ u-k with the assumption yl% is £lat between n.n (X <. o.li b - Dr (A&-5^ -)* bv-f^-^V) = o.os x 0,07 £^ : Efficiency to catch 2 u from kb in forward arm 0.75" = 0.5 r 4 C.2 : Efficiency of the trigger chamber 0.9 = 0.7 £3, Efficiency to detect the K. and p 0.7~ = 0.5 « During the discussion, where those results based on very simplified assumption were compared to more elaborate M.C. calculation (see T. Hansl - Kozanecki'pa- ?jr) it seems that this background could be overevaluated by a factor 10. Tliis point deserves a carefull check, but the author recognizes that the assump tions ace very crude °" t = 4-2 «L Even if the background is wrong by a factor 10 still there is a big factor (100 ?) between background and signal. trigger improvements could be considered - use the M pair correlations in d# decay (this was mentioned during the discussion). - use extra information from other parts of the detector f.i. . Low energy deposited in the central detector : events of peripheral type . High multiplicity in forward cones. Low multiplicity in central. Those schemes could help to reduce the instant trigger rate which could be very high : 1 evt/sec . M-b. Conclusion. A LL trigger can be set up in the forward direction without any complete reshuffling of the actual detectors but the meaningful identification of new signal will re1;; heavily an other properties of the other parts of the appara tus : - good momentum resolution i.e. good &m on ib mass - possible identification of K and p. It remains that this study is very restrictive and oriented on a single and peculiar decay mode. In many other cases, for instance the multi muon events observed in cosmics rays or other unexpected cases , the muon identifi cation could prove very valuable and significant over the background limitations.] For those reasons a rather efficient muon identification could be added in the actual set up with relatively small effort. r FICL'RK GM'TrOXS. l.ongi tudinal view of the forward and very forward deter Lu rs showing the position of the muon chambers which was assumed for Lhe calculation. Trigger efficiency to detect a single w from Lhc- du cay of I—> M-*" M. .•is ;i function of the Feynman X of the Aa Mean projected scatterirg angle of a muon as a function of energy behind either the CALCOM or the Very Forward calorinc Smearing of the image of the muon in the second plane of the trigger chamber as a function of muon energy. The smearing is due to a combination of scattering angle and magnetic rigidity of the track inside the CALCOM yoke. Scheme of a possible trigger electronics using drift signals of chambers and taking into account the smearing of the i^aue in the second plane. END CAP - Si — CALCOM ROME NO CHAMBER ! ) CHAMBER CENTRAL + CENTRAL ONLY + CALCOM + ROME + ROME ONLY (inside va- ! + ROME cuum pipe) ! X = 0.3 10 15 0 8 4 1 2 0 ! PT = o-o 20lb -r-Wi ( TRIGGER BEHIND CAI.COM BEHIND VFD (15) (15) ( CHAMBER 3 5 . 1 7 : 15 : 2 2:5 ! 3 \v -» 40 v» V ( TRIGGER BEHIND CALCOM BEHIND VFD (6) (26) VERTICAL SECTION ;ALCOM TRIGGER EFFICIENCY to detect a single p 100%- _^ -«—total efficiency ^- •>—detection behind V.F. 50% • ,*'^ 'X-- -, detection behind CALCOM 1. x Feynman FIG, 2 8 i i i I I I m rad Mean projected scattering angle behind filters 25 20 — \ \ 15 At - \ \ \ \ \ \ \ \ 10 \ \ - \ x \ X. 5 VFCt< ~~— " "" " ^* ^CALCOM + !( • I I I I 10 50 80 E.Gev FIG. 3 Mean spread in the 2nd. -100 \ plane of trigger behind — filters _ Ï 3 -60 \ \ O \ \ -40 \ X — -20 ""--^ ———-_____CALCOM~ , .---j-'"- 10 50 80 E.Gev FIG. 4 - 295 - r ELECTRONIC SCHEME FOR TRIGGER 20 n sec S-y 2 -» 1- plane 2-plane H u UJ TRIGGER CHAMBERS 1 e. >- w coinc.2-'Ii u J-v^ FIG. 5 INSTRUMENTATION DEVELOPMENTS AND POTENTIAL IMPACT ON COLLIDER DETECTORS. 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IlacCTtla af laalcaaAictlaa, flMt; Ï, Steal tuatt» 41 tarai a la i •*• aatvata •iKti^ai; 4, Caaaar atrlaat S, Optical |l«i> l»atta N iM»«»e»«/«««**i 20 .—- —:—r-~"""' 0 ^c . UCKV] •iaru i: Caaatlai chiTactarlatlc af • »tt» lac >lli«4 altckiri* /? ttCSU •: HtiiMai tluctuiUa*» la tlaa «alt>* KMH •*•(•(!*• *t *»a *r*tk canti» apaa tuit|. al tadl*t4**l catalc r*i> ptrtlOa» tt&*i *: aliiraa af tafaiaatia* raaaotit far eat«t*UaM at t**taia*iai aI l»u(i«a «I atttkdawa. 1. «raa •( at ••laaa* t? Flt&U 1: Ciwiil .i.» g( tilt ai Hijtit ipiclro**r*r; :.:.!.«.;.*. ;=IsiUJ«tiM coonttn SI. 51. SI. S«. :-, :•*; 7.1. U"?.r .«J Is-,f i?«rt cJiMban; B. ".II ef net» ikuur si VE»*-1« ito.-a*> darlcs ?« tccjmc nCMW 7: »lliri>>tl«» •!•«.»» «J • » •**ati a* tfca tla* lull "It* M Ci? s \(,r^,uu-j AfcÊ-A s «> 4»n x • 3 £** 2.2. i PSC-1 &>h- ' h vs ; jf RSC-2 * i, t -iMD -569 0 5» 1000 Ti»e dtfferejvce Lp«l -12 j^ 0 9 13 24 Irack residual [mm] PP COLLIDER AT FERMILAB J. "Us 6. So per Ccrvduc-K w\ "^^ YU^k Z, l/SÔ CL 'p CLccu nwlectu/v\ rc_k«.m.€. a. 0-St.ivc ffû-JôûÇs^ pY TO p fodLutt p Î b- Ost, phare spftci. coôlnvt C. Xyifto ' rt -Ls* —=* t( / • - 310 - £4L P '\CCoWLAThAT f taxiuef«*A X OCC 2/»^ «^ ÔT 0-CCV V»w C« V,) 3) *'» "t'.r** ftc«*-J-W«* vi) 7*WW. ft 4tuAK**v^ ojtlt ( C/M.I/2. ma) ê £loctas^V. TtovneA^V M CodUA-C *\sj} s \jjvcH~k o4 hv^kes* Sckofflu» 4Vw -ookk -ÇdW wim = u>il*k\ 3»v-P ?u==rTsir "^ ^^ P'Pi p p E5^ cU «*£*>*€. "fe tva^> ***»$-) crt$L Cool Cool Bu^tl •+I A.oh &?> 3.0 $tV>4*4. 8<.-A<^ Cû*l < Ê2; - 1 ^b»w^L^c' A 10 + 1 4 6 g frtfgffi » 3«fo Ces! G>.o«fv £.7 V p- r Fokker-Planck Simulation of Ap/p Cooling |.1W\ J^|V,1.«^ H•^H*3- Booster-sized Precooler Energy - 4.5 GeV Ho. of p - 5 » 107 Initial p spread - i2X n - 0.02 BW - 500 MHz (200-700 MHz) So. of P.U. - 200 Times shown: 0, 0.5, 1.0, 1.5, 1.0 sec. Gain - 1.5 » 105; Prearnp Noise Figure: 2db V4 turn separation between pickups and kickers Fig. 4-1 Computer simulation of notch-filter momentum cooling 1,5" £»eV/c CLfît â.r.a/p ecJt-tbW c^(3-*$ YWOY« ©* Collected 8. LdU3 jSipCalUcA tv^ leAlS — •ÇccdUv- ^ X -more utcnto C"^IK Hue *xio,Cj P €M f.o x w tr |^&_ LONGITUDINAL DISTANCE (m) Fig. 3-4 lixtracted-proton beam-transport layout. Antiproton Hall Q,o % MIIKIJU/Illllllllh. V///M •+-U O'D-gaa-B-r -e- -e- ^~~[nïùrNii)iiim)iç ~iwmr Fig. 3-5 p Hall and Target Vaulc JUi vv\M;titTb i)j -•% rtffu ^ c \iV...',..(' o 100- .5: o 3w \ 10- -o o o 3 r (cm) Fig. 3-6 I'r\i:ry,'/ distribution in a noroury t.ir^ut. ^ influenced by phase oscillations. The cooling of bunched beams nteds further analysis and evaluation before it is included in tha design. Figure 4-3 is a conceptual layout of the momenCura-cooling svsten for the Precooler. KICKERS i -\—t tiL-|-i:.;"r-:iu i—i—» A-5. CONCEPTUAL LAYOUT OF PRECOOLING SYSTEM •3- *-\ H-+- -i—* / 36.48 m R=52.25m + *+«f- -+-+- -f-l—M Precooler Layout Fig. 5-1 - Dipole magnet I Quadrupole magnet 20m/inch -f Table 5-1 Precooler Parameters Superperiodicity 4 Long drift sections, disperion free length 20.2 a nunber 4 Drift sections, disperion matchi ng length 2.3 m number 16 Average radius 75.47 m 3etatron tunes vx 10.7 11.7 Phase advance per normal cell 90° Transition t 9.63 Revolution period (at 4.5 GeV) 1.6 ii s Dispersion n - (a t/c)/ (ip/p) 3 4. 5 CeV 0.02 « Orbit functions, maximum values Ix 53.5 m ry 28.1 m Xp 1.1 m T ->.r:tice structure Half cells Dr : QD 0 B 00 B 0 QF FD: Qr 0 B 00 8 O QD Hornal cell C: DF FD Dispersion Hatching all CX?: QD 01 B 02 QF 02 B 0 QD Half straight sections SS: QFA 00 ÇDA QDA 03 QFB 04 QD3 LL Octant OCT: C C C CXP DF SS Ring RING : 4 (OCT OCT) Lattice components bending magnet B field at 8 GeV 9.35 kC length 1.52 m gap height 6.0 cm gap width between coils 16.0 cm copper weight (raw material) 200 kC iron weight (raw material) 1500 kG number used 123 normal quadrupoles 2QF, 2qD 2QDA gradient at 8 GeV <160 kC/m length .61 m pole-tip radius 4.8 cm pole-tip field <7.8 kG copper weight (raw material) 100 kC iron weight (raw material) 1100 kC number used B0 special matching quads QFB. QDB gradient < 137 kG/m length .91 m pole-tip radius 7.0 cm pole-tip field <9.b kG number used 16 - 323 - î ^V «?° ~ 3 o >7î ^ y 'h !.., ' TtiiWÎ&e^ ? ? ? * propos»^ T û ' ^ f~uîu£é T)£v/£ To Tv*$>£40fc LwMiWMiTT 1, FAST STOCHASTIC L%L L*/w$ 3. Hi TOPICAL WORKSHOP ON FORWARD PRODUCTION OF HIGH-MASS FLAVOURS AT COLLIDER ENERGIES COLLEGE DE FRANCE November 28, 29, 30, 1979 LIST OF PARTICIPANTS. ASTBURY, Alan, Rutherford Lab., Chilton Didcot (U.K.) BENZECRI, Paris VI, Paris BORDES, Gisèle (Mrs), Collège de France, Paris CALVETTI, Mario, CERN, Geneva (Switzerland) CATZ, Philippe, LAPP, Annecy-le-Vieux CERADINI, Filippo, Istituto di Fisica "G. Marconi", Rome (Italy) CHAHINE, Charles, Collège de France, Paris CLINE, David B., University of Wisconsin, Madison (U.S.A.) DELPIERRE, Pierre, Collège de France, Paris DENEGRI, Daniel, D.Ph. P.E., CEN Saclay, Gif-sur-Yvette DIAMANT-BERGER, Alain-Michel, D.Ph.P.E./SEE, CEN Saclay, Gif-sur-Yvette DOBRZYNSKI, Ludwig, CERN, Geneva (Switzerland) DOLBEAU, Jean, Collège de France, Paris DOWELL, J.D., University of Birmingham (U.K.) DRIJARD, Daniel, CERN, Geneva (Switzerland) EGGERT, Karsten, CERN, Geneva (Switzerland) EQUER, Bernard, Collège de France, Paris FONTAINE, Gerard, Collège de France, Paris FONTANNAI, Michel, L.P.T.H.E., Orsay FREHSE, Hartraut, CERN, Geneva (Switzerland) FRITZSCH, Harold, Université de Bern, Bern (Switzerland) FROISSART, Marcel, Collège de France, Paris GAILLARD, Mary K. (Mrs), CERN, Geneva (Switzerland) GAVELA, Legazpi, Ecole Polytechnique, Palaiseau GEIST, Walter M., CERN, Geneva (Switzerland) GHESQUIERE, Claude, Collège de France, Paris GIBONI, Karl, CERN, Geneva (Switzerland) GIRAUD-HERAUD, Yannick, Collège de France, Paris GIVERNAUD, Alain, CEN Saclay, Gif-sur-Yvette GRARD, Fernand, Université de l'Etat, Faculté des Sciences, Mons (Belgium HANSL-KOZANECKI, Traudel (Mrs), Physikal. Inst. B. RWTH, Aachen (Germany) HERQUET, Philippe, Université de l'Etat, Faculté des Sciences, Mons (Belg HOFFMANN, Hans, CERN, Geneva (Switzerland) HOFFMANN, Dieter, Physikal. Inst. B., RWTH, Aachen (Germany) ICHOLA, Alimi, Laboratoire de Physique théorique, Amiens - 326 - KELLER, Mirella (Mrs), CERN, Geneva (Switzerland) KERNAN, Anne (Mrs), University of California, Riverside (U.S.A.) KESSLER, Paul, Collège de France, Paris KLUGE, Erik, Inst. f. Hochenergiephysik, Heidelberg (Germany) KOZANECKI, Witold, University of California, Riverside (U.S.A.) KRYN, Didier, Collège de France, Paris LALOUM, Maurice, Collège de France, Paris LF.HMANN, Pierre, D.Ph. P.E., CEA Saclay, Gif-sur-Yvette LERUSTE, Philippe, College de France, Paris LEVEQUE, Antoine, D.Ph.P.E., Saclay, Gif-sur-Yvette LINCLIN, Denis, LAPP, Annecy-le-Vieux LOCCI, Elizabeth (Mrs) D.Ph.P.E., CEN Saclay, Gif-sur-Yvette MATTI, Djillali, Collège de France, Paris MENDIBURU, Jean-Pierre, Collège de France, Paris MULLER, Francis, CERN, Geneva (Switzerland) MURAKI, Yasushi, Inst, for Cosmic Ray Research, University of Tokyo (Japan) NARJOUX, Jean-Louis, Collège de France, Paris XICOLAIDIS, Argyris, Collège de France, Paris NORTON, Alan, CERN, Geneva (Switzerland) ORKIN-LECOURTOIS, Agnès (Mrs), Collège de France, Paris PETERSON, Carsten, Nordita, Copenhagen (Denmark) PETRONZIO, Roberto, CERN, Geneva (Switzerland) PIRE, Bernard, Ecole Polytechnique, Palaiseau PRENTKI, Jacques, CERN, Geneva (Switzerland) and Collège de France PLTZER, Alois, Inst. f. Hochenergiephysik, Heidelberg (Germany) RADF.RMACHER, Ernst, Physikal. Inst. A., RWTH, Aachen (Germany) REPELLIN, Jean-Paul, LAL, Orsay RrCH, James, D.Ph.P.E./SECB, CEN Saclay, Cif-sur-Yvette ROLLINCER, D.Ph.P.E./SECB, CEN Saclay, Gif-sur-Yvette RUBBIA, Carlo, CERN, Geneva (Switzerland) SADOULET, Bernard, CERN, Geneva (Switzerland) SAJOT, Gérard, College de France, Paris SALVINI, Giorgio, Istituto di Fisica, Rome (Italy) SASS, M., D.Ph.P.E., CEN Saclay, Gif-sur-Yvette SAUVAGE, Gilles, LAL, Orsay SCOTT, William G., CERN, Geneva (Switzerland) SENS, J.C., CERN, Ceneva (Switzerland) SOSNOWSKI, Richard, High Energy Physics, Inst, for Nuclear Research, Varsaw (Poland) SPIRO, Michel, D.Ph.P.E., CEN Saclay, Gif-sur-Yvette TAO, Charling (Mrs), CERN, Geneva (Switzerland) THOMPSON, Graham, Queen Mary College, London (U.K.) WROBLEWSKI, Andrew, High energy Physics, Inst, for Nuclear Research, Varsaw (Poland) YVERT, Michel, LAPP, Annecy-le-Vieux ZACCONE, Henri, D.Ph.P.E,/SEE, CEN Saclay, Gif-sur-Yvette ZYLBERSTEIN, Armand, CEN Saclay, Gif-sur-yvette