Beutrino Interactions - an Experimental Surrey
S. SanerJee lata Institute of Fundamental Research, Bombay
1. Introduction
In the past few, years, enormous progress has been made in experimental V physics. With new results coming in from the SPS and the Serpukhov machines in addition to the Fermilab X facility, the studies have produced breakthroughs in a number o f f ie ld s . Before going to the results let me mention a few points on the precisions in these measurements. The CERH SPS and the Fermilab groups now u se a dichrom atic narrowband beam In addition to the wideband beams. The purity of the beams has gone up; th e wrong type X con tent ( P in V beam or V in V beam) is typically 2-32 and Vfi( Ve) contaminations are 1-2/. Furthermore the beam energy is fairly well, determined from the d ista n ce o f th e in ter a c tio n v ertex from a cen tra l beam a x is (for V 's from K decays, the uncertainity in this determination is •>» &X). The narrow band beam spectrum is much broader than the wide band spectrum and consequently the average beam energy is higher 75 GeV c f TO «v 30 GeV). However th e fluxes are reduced by an order of magnitude. The V -fluxes are determined by various techniques. The uncertainity in the absolute flux determination is 7? for V 's from n-decays and is 10-122 for V 's from E-decays. The detector systems used in the measurements can be broadly divided into two classes, the large bubble chambers and the electronic counter setups using huge hadron calorimeters and fx-spectrometers. The main features of these two detectors are summarised in table 1.1. The detector configuration in the * - 171-
SPS beam line is shown in fig. 1.1.
The kinematic variables used in the- subsequent sections are defined in figure 1.2.
B = energy of the incoming V B = energy of the leading outgoing lepton {ji in th e case of charged.current interactions) V = E-E = energy transferred to the hadronic system q * 4—momentum transfer - at the leptonic vertex 2 2 Q = -q = mass squared of the off-shell VtUboson
'V A. y - B 9 0 dimensionless scaling variablfes _ Q2 X ' x M = nucleonic mass
2. Charged Current Interaction
- Most of the recent results in charged current interaction come from deep inelastic scattering of with a nucleon target, i • 6#
VN - p ~ jl . _ ■ + - 2.1 V N -* y. x
There are also some new results in exclusive studies like quasi elastic process, single pion production etc.
2.1. Exclusive Studies A. Quasi elastic channel: Data on quasi elastic channels V n - u“p and V p - u+n have been used to study the axial vector r P ' form factor. All the analyses £2.13. assume CVC and dipole form
factor for the vector component with = 0.84 GeV/c2. The axial - 72
coupling was taken to be 1.25' (froin p decay) and the axial form factor was also assumed to'be of dipole type. The: results'are summarised in figure 2.1. The reaction, v p--* ,A++ was also studied £2.2j in the frame work of Adler Model £2.3}. The value
o f Ma is converging to a value slightly higher than M^. One should note that the current value of the coupling constant is slightly higher than ,1.23 and the dipole form of the vector component is known only within at low Q2 (even worse at large Q2). " . . . B. One nion prr-duction; The ANL groups £2.4] has studied single pion. production in deuterium from threshold to E = 15 GeV. The reactions looked at are
V p - p~p 7t+
y n - ^"*n n + 2 .2
Vn - ^i-p n°
All three final states show strong £ -production suggesting a dominant isovector current. The analysis leads that the inter ference of the I = 1/2 (A1) and.the I = 3/2 (A^) components is needed to explain the data. However the data are consistent with a zero isotensor component. Assuming a zero isotensor current | A. I they obtained | - 0.57+0.06 and the relative phase 0 = 89.2+8.7 degrees. _
2.2 Inclusive Studies- In a *V-A theory,- the differential, cross- section can be written in the absence of AS / 0 and AC- / 0 c u r r e n t as where P^' s are the nucleonic structure, functions. The relation is very similar to that in. the deep inelastic scattering of e or jx with nucleons. The extra term F^ comes from V-A interference and it changes sign from to V . At high energy one neglects M . " ^ terms and rev/rites 2.3 as ■
„ * „ e <&*> - — RV& a‘> * FLV:1,cx,eL) v
There are several simplifying ideas involved in the analysis of the data.- The most important-ones'are listed below
(1) Charge Symmetry: For inclusive processes, this leads (for. h S = 0,Zk c = 0 c u r r e n t)
F / P = F ^ n and F .5 ? = F^v n - 2 .5
■ For isoscalar target this is simply ?? = F ^ •
(2) Callan-Gross relation: Assuming th i spin-structure of the constituents, this relation gives 2xF1 .= F2 2.6
These two relations simplify 2.3 as
d ^ VlV a V it d x d > - ~TT Ck {1+ a - » zj F^> \ In quark-parton model, the structure functiofi are related to the' parton distribution functions. (F2J^F^) gives the scatter ing of V on -quark (or V on q). ^(FgTxF^H 1-y)2 gives'the . scattering of V on q (or i> on q). F2(x,Q2) signifies the momentum distribution of all quarks and antiquarks in the nucleon and xF^(x,Q2) Signifies the momentum distribution of the valence q u a rk s . Thus ^ ==5S [Q(X,Q2, *5U,Q2)(1-y)2:l ^ - 5 ^ I8(i,a2)«X«.ii2)(i-7)2J. One other important notion Is the Bjorken scaling. This 2 V states that in the lim it of E — °°, Q — 00 and —* — finite, the . Q hadronic structure functions are only functions of x. The scaling leads that the total V (orP) cross section on nucleons would have a linear energy dependence like the V -lepton scattering. Now reverting to the experimental data, one can broadly classify the results into two categories (1) integrated quantities (e.g. total cross section, A. Total cross-section: New data [2.5] come from (1 ) SPS narrow b an d beam ex p e rim e n ts (2 0 -1 9 0 GeV) by CBHS and BE3C, (2 ) FNAL narrow band beam ex p erim en t (2 0 -1 9 0 GeV) by CITiFR, ( 3 ) Serpukhov wideband beam experiment (8-30 GeV) by SKAT and IHEP-ITEP, (4) AN! 12' bubble chamber experiment. The D-data (fig .2.3) siqgsst a constant slope ((T/E) over the entire energy region. BEBC and CITFR data may suggest a slight increase above E = 80 GeV. The - 75 y-data at energy above 50 GeV have a constant slope. But lo.wer energy data indicate a decrease in slope, from 10 to 50 GeV. Fig. 2.4 shows the ratio of v to V cross section as a function of energy. The HPWP points show a systematic increase with, energy which is present on a much reduced scale in BEBC and CITFR data whereas it. is absent in the CDHS data. This discrepancy could be due to the different acceptance cuts in the different experi ments and the model dependent corrections to take into .account this effect. Gargamelle propane group (PS energies) and FNAL Michigan group (j2.6j studied the ratio ^ for P'~ At energies below one pion threshold, this ratio should be zero. Valence quark contri- bution.leads to a value 1/2. Correction from sea shifts the ratio to 0.6. It is difficult to'choose between the two with the present data (fig.2,2). B. Mean Squared Momentum; th is parameter aiid the value depends on the method _employed. The ,~.v,v - CDHS group [~2.7] has filled the y-distribution ^ ------1-( 17-BV’ )y *(1+B^,5 )y^ assuming a constant B. The BEBC collaboration /x F * d x v obtains B = jygg- = ' ~ i • This method takes into account 2 6" ^ ^ y-dependence of B but assumes B = B (i.e. charge symmetry). The CITFR group [2.83 fits both zero and first moments of y to obtain B. The data are shown on.figure 2.7 for V . The HPWFOR group has reanalysed their data and their new results are consistent with other experiments. Bv is flat above E=s50 GeV. ,B. D ifferential distribution '(i) Test of Charge Symmetry: Charge symmetry for F^ h a s been tested by looking at in H and V interactions /d6fiv / dS'i*'\ j _ 1.05+0.07 in CDHS experiment ( $y' y=o I'3 6148 ^ 0.90+0.20 in BEBC experiment CITFR group studied this as a function of energy and it was found to be good within 5/. CDHS group .[2.6, 2.93 looked at the y-distribution for testing charge symmetry in xF^. The results of the analysis are shown in figure 2.8(a). and (b) at two different energies. Separating 2 — V the flat part from the (1-y) part at y=0, one measures Q whereas for 5 distribution, the cross-section at y=1 leads small Q2 and QV at high Q2. QCD suggests (fig .2.8c) for small x values antiquark content is more at large Q . 2 So' this • difference could, simply be a reflection of the scaling violation. (ii) Test of CalIan-Gross relation: Here one defines a-parameter f ] 2xF. dx A = -2 ------1 - 2.12 This parameter is expected to be 1 if the Callan-G-ross relation is true. BEBC-Gargamelle data have been studied in bins of x and q2 and shown in fig .2.9. CITFR extracts the information from the moments of y distribution,M ean values of 1—A is summarised' below 1-A : 0 .1 1 + 0 .1 2 Q2>1 GeV2 BEBC 0.17+0.01 Q2>1 G’eV2 CITFR 2.13 < 0.05 with 90X CL (iii) Sea contribution: The term XF^ ( aquation-2.3) in V and v interaction appears with opposite signs. This helps the separation of the sea from the valence quark. Also charm-changing currents can be used to estimate the strange sea contribution in the nucleon (i.e. from dilepton studies). The extracted values are summarised in table 2.1v It suggests the sea is probably not SU(3) symmetric. (-iv) Nucleon Structure Function: Assuming charge symmetry and fixing-a value for:-A*.,one can combine v and v data to extract the-nucleon structure functions. CDHS and 3EBC' "groups [2.6, 2.9, 2...1 Oj have studied this field extensively. lo cover sufficiently - 78 2 large range of x ,and Q , the BEBC group combined their =data with GGM Freon data in wide band V beam at PS energies. Fig.2.10 shows, the structure function integral as a function of Q2. Both F2 and F^ show a strong 2 dependence suggesting the breakdown of scaling. The Fg's evaluated by the BEBC gtoup have a very 2 sim ilar Q dependence with the Fg's obtained from e-d and ^i-p scattering data [2.113, the absolute values’ differing ^y a factor 5/9. At large Q2, one finds that the integral / Fgdx- deviates sufficiently from 1 suggesting a significant gluon contribution. The more interesting aspect of the analysis involved a comparison of the higher moments of the structure function with the theoretical predictions. The Cornwall-rNorton moments £2.123 are defined as Mjj(Q2) = /J xN~2 F1(x,Q2)dx 2.14 2 * The moments fall off at large Q . It is expected- that part of the decrease is due to mass correction terms of order M2/Q2 which are absent in the Bjprken lim it Q2 -* °°. So one redefines the moment in terms of a variable^* * _ 2x 2 .1 5 ■ 1 ^ / q ' ^ to take into account, this effect. The Nachtmann moments ,[_2.153 can be written as p ■ ' O 4 £ B +1 Q M2(Q2) = fl F (x ,Q 2 ) X f(N2+2N+5l+5(N+1 )7l +4M2x 2/Q2-HT(H+2)4M2x 2/Q2Jdx (N+2) (N+3 j - 79 - g«»a ) 2.16 x For 1T = 2 moments, the contribution from the low x - values "is significant and the correction for the experimental biases makes , the measurement unreliable. However higher moments do not suffer ftom this lim itation. The moments obtained have been looked in liglit of Asymptoti cally free gauge theories £2.143 for strong interactions. There . are 2 flavour singlet terms corresponding to sea quark and gluon distribution and 1 nonsinglet term for the valence quark. The function xF^ is a pure non singlet and so the predicted dependence is of simpler form MN(q 2 ) = V SKA. 2 -17 ■ (InQ /A • - N—2 - where \ = D- nfir+1 j* I » m ='number of quark flavours. Fig.2.11 shows a plot for In against In M^, for a choice of N* and N". The linear dependence of the two function is expected from the theory. The slope is exactly predicted by the theory and it involves only the number of quark flavours and the gluon spin. Comparison .of the slopes from theory and experi ment is done in table 2.2. The agre'ement with the vector gluon type is remarkable. The Q2-dependence is studied in figure 2.12. Large Q2-data clearly show a logarithmic dependence. However higher order corrections £2„ 153 > change the shape of the predicted curve at small Q2 values. So evaluation of A,(obtained from the intercept of the curve) is not very precise. Including only first ordered correction one gets A = 0.74+0.05 OeV with - SO - the second ordered correction, put in, A =0.40+0.025 GeV, 3. Neutral Current Interaction ' Since the discovery of neutral currents in 1973 [j.l3» much effort has gone into the understanding of the structure of the" neutral current. The related data come from four distinct types of experimehts (1) experiments using high energy ^u. ( ) hearns in the accelerator laboratories (2) experiments using low energy Ve beam in the reactors, (3) atomic physics experiments studying the parity violating effects (4) experiments studying, parity violating effect in electromagnetic scattering processes. In the analysis of all these experimehts, one starts with a framework given by Weinberg and Salam [3.2} involving a weak isospin and weak hypercharge in an SU(2)xU(l) model. The general form of the effective Lagrangian can be written as for pure lePtonic Process for semi leptonic proc.ess. The quark coupling constants u^, uR, dR are alternatively written (3.3) as 3 .2 In Weinberg-Salam model, ail these coupling constants' can be written in terms of a single parameter sin 0^2 —81 - u L- ± _ | s;ni®w , d l= -5 .* ss,ndw , -i +2sin% , 3,3 3.1 V-e Scattering: y-e scattering involves only lepton vertices and the analysis is relatively pure. However the low cross-section causes a. low event rate. The data £3.4,3.53 are summarised in table 3.1. The reaction is mediated only through neutral current. So the cross-section can be written as dy^“ = [(gv+SA)2-Kgv:?gA)2(l-y)2-Kg^-g^)Me I ] 3 .4 i-gg scattering can also go through charge current phenomenon. So in the coupling constants one should effectively have 1 -tgy and 1 -tgA instead of gy and gA respectively. The low energy 6 data from Gargamelle and Aachen-Padova have a strong sim ilarity with the high energy data from the Columbia-BNL . group. However the high energy Gargamelle data are inconsistent with these experiments. All these data are consistent with ( f i g . 3 .1 ) Sv = 0 .0 + 0.1 ; g A = - 0 .5 + '0.1 2 i.e . Weinberg-Salam model with sin 6W = 0.23^0.05 3.2 Inclusive, hadron production: The quantities measured in the reaction are: Rv = -CO^? • . D = 6^-N-^.) • 3.5 6"(^N-^a x ) er(3N-^u x) The bulk of the data comes from isoscalar targets and are . summarised in table 3.2 £3.5,3.63. Extraction of information from this process involves a quark-parton model' framework. The - 82 - analysis involves assumptions regarding the sea content in the nucleon and also QCD effects.. In fact the dependence of quark density function on causes the,disagreement of R„(Ry),in various-experiments (due to the variation in . averaged value' of Ry and Rjj , one obtains for the,quark coupling c o n s ta n ts UL + dL = 0.29 > 0.02 •; 2 2 «r + 4 = 0.02 -2 o.ov . corresponding to sin% w = 0.23 + 0.03 The BEBC group C3.7] has looked at the hadron energy distribution. They defined a variable y* in analogy with y, as R. y ' ' 3 ,6 where By(R) = the mean energy at a radius R. from the i) -axis, (the event occurring at that radius) y' is the same as y for events, whereas y‘ < y for ^ e v e n ts . Knowing the beam spectrum, one csin get a correspondence between y1 and y,distributions. Assuming the. tensor contribution to be zero, one finds the strength of PS and S contribution relative to that of V and A to be less than 0.12 at the 95X confidence level. The data are not yet sensitive enough to distinguish a tensor contribution from the V and A contributions., Using V and A type interaction and neglecting the AS = 1 . current, the y' distribution has,been.fitted in terms of 3 coupling constants u£+d£ = O.34+O.O3, u^+d| =0.024+0.024; <*l^R °*19^*19 In terms of Weinberg-Salam model, this corresponds to sin^9w = 0.19+0.03. Inclusive scattering on proton [3.8l a re summarised in table 3.3i This should in principle give the difference'of u and d couplings. But more precise measurements "are needed. 3.3 Exclusive Channels in y N scattering: Here the data exist mainly in elastic scattering studies [ 3 .5 ,3.3 and single pion production [ 3 ,5 , 3.1$ Elastic scattering has been studied in CERN PS energies by the Gargamelle and Aachen-Padova groups and by two counter groups at BHL. The results are summarised in table 3.4. The. data support a strong isovector component of neutral.current and the value obtained for sin 9^ = 0.22..Single pion production data come from Gargamelle propane experiment and the main feature in the data is a clear signal, of A (fig .3.2).. This supports a dominant isovector current. The cross-sections are tabulated in table 3.5. The difference in V.pit0 and V nit0 cross-sections indicate an interference of isoscalar and isovector c u r r e n ts . 3.4 Semi-inclusive measurements: The charge ratios of pions produced in neutral current experiments give a handle to the isospin structure of. the current. The data from the Gargamelle collaboration C3-1 "0 gives (x+/it~) = 0.77+0.14; =1.64+0.36 All the data have been systematically studied by Abbott-Bamett ^.12] and the solution for the quark coupling constants are summarised in table 3.6. 3.5. Atomic Physics Parity Violation Experiment: In presence of parity, violating current one. expects to observe small optical rotation of the plane of polarization of light passing through bismuth vapour at frequencies for which am interference■due to ..weak.neutral current is allowed. Three experiments have been done at Seattle, Oxford and Novosobirsk £3.12) . The value of the angle of rotation■of the plane of polarization have been compared with the theoretical'- expectation from Weinberg-Sdlam model (with siri^9w = 0.25) in table 3.7. Seattle group has a clear disagree ment' whereas 'Novosobirsk group agrees with th£ model pretty closely. The experiments are very difficult and one needs a inore careful study (both in experimental set-up and in"theory) before drawing any further conclusion. 3^6 Polarized electron scattering: SIAC-Yale group studied the asymmetry in longitudinally polarized electron scattering off deuterium target [3.14). ^he experimental set up is schematically shown in figure 3.3. linearly polarized light is produced from a dye laser and is passed through a Pockels cell to transform it to circularly polarised light.’This circularly polarised light in its turn produces.longitudinally polarized electrons in Ga-As crystals mounted on the electron gun. Depolarization is negligible during acceleration and the magnitude and sign of polarization is measured from asymmetry in Moller scattering from a magnetised iron foil. One' observes non zero asymmetries both in deuterium and in hydrogen. A/Q2)d = (-9.5+1.6) XIO-5- (GeV/c)-2 . A/Q2)h = U 9 .7 + 2 .7 ) x IQ "5 (G eV /c)“ 2 - 85 - The re'cu^ts agree pretty well with sin^9w = 0.20+0.03. However the experiment has a limited coverage of and y. Variation in these parameters can settle the issue on Weinberg- •Salam model, is a conclusive way. All the data described here can be consistently fitted is with a Salam-Weinberg type model .with sin^9w = 0.23+0.02 (see figure 3.4). 4. Final states The scaling violation observed in the charged current reactions has given.some insight to the structure to the nucleon. There the study was confined to the leptonic vertex only. Obviously one would get more information by studying the hadron vertex. The hadrons produced would be intimately related to those produced in eN,y N, and hadron-hadron collisions. Several Bubble Chamber groups £4.1J have#carried out analyses of these- hadrons in the light of the quark-parton model. 4.1 • Fragmentation Function The quark-parton model predicts that the differential distribution would factorise in the variables x and z (z is the fractional energy of an individual hadron -= E^/Ey) i.e. ' lib* GNq,(x,q2:)i£(2) ■ ■ 4.1 where gives the distribution of quarks inside the nucleon and z) is the fragmentation function of the scattered quark q. The fragmentation function is normalised as f l B*(z)dz = 4.2 pT Distribution ' ' The prp distribution (Fig.4.6) cannot be well parametrised by a Gaussian (as in the FF model). Rather a fit of the type e"tmT (where m^ - transverse mass = >/m2+p^) with b = 6 explain 2 2 the data farily well. has been plotted as'a function of Q in fig.4.7. The v data and wideband ^ data do not.show any 2 2 significant dependence on Q . The phase space pulls down ■ 2 2 100 GeV and z at 0.2, one clearly sees a rise in This rise of spherocity,thrust variables £4.3j- Spherocity,-thrust are d e fin e d as . Z | p— . | p S = ( | ^ |^X| -) for minimum £ IPyil lip.. . | (summation done .over- : T = 2 ( . ) " ^ Z |p^|maximum one hemisphere) where^ p T ^ and p,*£ are transverse and longitudinal momenta of the hadron i. For two jet formation S would fall off whereas T goes from a value 1 in two jet configuration to a value 1/2 in spherical configuration. Fig.4.8(a), (b) show Sterman and,Weinberg [4.43 have defined a two jet event as an event that has more than (1-4) of the energy within a cone of opening half angle 6 , They have calculated the fraction of such events in. the case of e+e” annihilation (1-F) would be by definition the fraction of three jet events. The energy dependence tak es th e form = Gfe ,6 ) [ y | In (^ 2 )+ 11 4-.5 Assuming a sim ilar energy dependence to exist for the yN case, the BEBC group has plotted 1 as a function of Q on2 a semilog plot for various £ and 6 (Fig.4.9). The data show an approximate linear dependence with a common intercept at A = 0.4. All these studies corroborate the earlier study of quark structure function. 4.3. Other studies There have also been several studies to look for resonance P * 6 » Aj e t c . [4 .5 J in the charged current interaction. The AML-Carnegie-Mellon-Purdue group [4 .5 ] has looked for all charged current events with a V° in 5 exposure at FNAL 15* chamber. The rate. of. V° events has been found to be large at small x-values. The.rate is very well explained by charm decays (fig.4.10). 5. Multilebton Production 5.1 Unlike charge dilepton Dilepton production by U was first observed by the HPWF group in 1975 £5.1J , in the dimuon. mode. Since then several groups have observed the dimuon final states (5.2]t Since muon identification utilises its long lifetim e and small cross section the observed muons have a large momentum cut off (at 4-.5 GeV/c). With the availability of the large sample one can now Ipek at' the energy dependence and various other distributions to study the production mechanism. The bubble chamber groups have observed the dilepton events'in yet another mode (namely ^ e - .mode). There the. electrons are observed with a larger momentum acceptance (momentum cut off fs at 0.3 GeV/c). Correlation with strange particles can also be observed. The observed dilepton events are smmnarised in table 5.1. Before going to the analysis,the various mechanisms to produce dilepton events are briefly discussed. The first mechanism (fig .5.1a) involves the production of intermediate vector boson which undergoes electromagnetic bremsstrahlung and decays leptonically to give rise to dilepton final state. The second process is the so called weak trident process and goes according to figure 5.1b. Here the typical rate is 10 J tim e s the total neutrino cross-section. A third possibility is the production of a heavy neutral spin 1/2 lepton which subsequently decays leptonically (fig.5.1c). This characteristically has a - r * 9 0 ■ Pi bound £5.3j on the asymmetry of the two lepton momenta. (.48< — 2 < 2.1). The fourth possibility is that at the hadron vertex a new particle is produced which decays weakly to leptons (fig.5.10) This is a process predicted by GIM model, in which a fourth quark, the charm,' is added to the u, d, X quarks. The charm production ■ - 2 off a Valence quark is suppressed by sin ©c with respect to the normal transition of its production off a sea quark. .XLso th e number of'strarige 'particles produced along with the dilepton event is 1 when it is produced off valence quark and is 2 when it is produced off sea quark (see figures 5.1e). The first experimental observation is that both dimuon and ^te rate increase rather fast with energy, the rate being 0.5/'. of the charged, current interaction (figure 5.2). This rules-out the weak trident process as the main mediator of such events. The second lepton (with wrong sign) has,pn the average, much smaller momentum GeV/c f o r e le c tr o n s and -10—15 Ge-V/c f o r muons,, with p^ cut at 4.5 GeV/c), compared to that of the first lepton (pq~ 50 GeV/c). This rules out the direct production of inter mediate vector bosons or heavy leptons as the only source-of these events. The> most likely interpretation seems to be the production and subsequent decay of charmed particles in the GIM schem e. Some quantitative comparisons are made with a 10X le p to n ic decay mode ,of charmed particles. This leads to a 5/ charm 2 production which is on the same level as expected from sin 9C. The second lepton has a momentum typical to the hadrons in the shower, also it has a small p^ with respfect to the .hadron shower 91 direction, x and y-distributions (fig.5-3A) of these events' closely resemble the'normal "charge-current distribution. 5 can produce charm from sea quarks whereas V can produce charm both from sea and valence quarks. So one1 expects . 5 .2 Trinaion production " In 1976, the CITFR group C 5.4} first observed a trimuon event. Since then the HEWE group at and the CDHS group at - SPS have observed a reasonable sample of such events.. With this increased sample size f5.5, 2 .9J one can now study the origin of these events. Regarding its production mechanism, there are in principle two different models involving the production- of new particles: (i) Production and cascade decay of new heavy leptons at the lepton vertex (5.4a) (ii) Production and subsequent decay, of quarks with new flavour in the shower (fig 5.4b) - 92 - . More conventional sources, for trlmuons are normal charged current ■ events with an additional muon;pair. There the. two main possibili ties involve (1) Internal br emsstrahlung of the leading muon ox of one of the quarks (IB -see fig.5.4c).. (2) Hadronic production of the muon pair in the shower (HMU-see fig.5.4d)., Y The increased sample size comes from mainly two new experi ments at CDHS and HPWIfOR. The dominant background to these events is due to dimuon events with a decay. After correcting for such background, one sees a signal in mode for if and mode for 3 and the rates are summarised in table 5.3 and figure 5.5. The rate increases by a factor 10 from 30 GeV to 130 GeV. This is mainly due to the muon detection threshold of 4.5 GeV/c.The leading muon is chosen in a way such that the transverse momenta of the two other muons with respect to the direction of W (i.e . q) is minimum. With this definition of the leading muon, one plots the effective mass of the remaining muons (figure 5.6). It has a low mass enhancement characteristic to the internal bremsshrahlung and hadronic muon pair production mechanism.. The transverse momentum of the pair with respect to the direction q again peaks at small values. The heavy lepton cascade cannot explain these two distributions simultaneously (see fig .5.7). The dominance of the HMU mode is. very clearly seen in fig .5.8 where one plots the azimuthal angle between the leading muon and the remaining muons in a plane perpendicular to the V direction. The peak at 1dO° is due to the HMU mechanism. However there is a cluster near 0-0 which is attributed to IB. Using this distribution one separates out the contribution due to IB £r = (,8+.4)x10 5 from the contribution due toHMU (R = (2.2+0.4)x10~'’J, which agree —5 —5 reasonably well with the-predictions namely .7x10 <®ib<' 2 x 10 . and Rhwt> 2x 1 O-^ for E > 30 GeV. Thus all the’ events in the trimuon production can be explained by charged current interaction with Internal bremsstrahlung and muon pair production-in hadron, show er. 5.4 like sign dimuons like sign dimuons are of interest in the-light- of heavy lepton or heavy quark cascade models. One expects more like sign dimuon events than trimupn events. The. observed like sign dimuons [ 2 .9 » 5*2] sire summarised in table 5.4. The main background to these events come from n/K decays in flight. The background has been studied by the CDHS group using Monte .Carlo technique whereas HPWFOR group studied the rate at various target densities and then extrapolated" to infinite .density. The calculated rates after background subtraction are also shown in table 5.3. The data s till need more refinement before any fiirther conclusion can be draw n. 5.5 4-Iepton final state Three groups [ 5 .8, 5.91 have reported so far a candidate for 4 lepton events. They are summarised in table 5.5. A typical event is shown in figure 5.9. The most substantial background in - the 4-u events is due to trimuons with an extra x — p or K-p -2 decay in the shower. It would typically give ~ 2x10 events. 94 The, origin of such events could be due to the. process IS and HMU w ith an associated charm, production or charm production' as in . . dimuon events w ith an, associated charm pair production. There are obviously suggestions requiring new, particles (i.e. new leptons or new quarks).. The expected event rate from conventional sources _7 is 0.2 event.for the 4—^ events and 10 event for the bubble •chamber experiment. One needs more statistics to get further - clarification^ 6. Direct Observation of Charm, heavy lepton etc. 6.1 Direct observation of charm . Charmed p a r tic le was observed in a hadronic decay mode by the Columbia BN1 group (jj.6]. They looked for all charged.current events with a V° decay. The K° mass plot (fig.6.1} clearly shows a bump (4 standard deviation effect) at 1850 MeV (the region of D as seen at SPEAR), A ganssian of mean 1850+15 MeV and width 20^8 MeV fits the plot. The corresponding mass plot for neutral current does' not show that peik,indicating a suppression of. charm charging neutral current. 6;2 Charm-Changing neutral current CDHS group £6.13 has studied the wrong sign muon events to investigate the existence of the charm changing neutral currents. The Columbia-BN1 group studied events w ith an e + but no yc • in V ^ ■ sample to investigate similar effects. After correction for l^Cor .Vg)’backgrounds, no candidate was left over and both the groups have put an upper lim it. - 95 - CDHS upper lijmt Slch^ hagging^C l < 2i6Jf Coi-BH, Up p = , U n i t < a .6 Z 6.3 Heavy Lenton Production OIHS group €6.1} has used the single ^i+ events to put upper . lim its on charged heavy lepton production of muon type, the lim it being best summarised, by- figure 6.2. From single electron .events Oolumbia-BHl group f5 .6 j puts a 90X confidence lim it on ’mass (l”) to be larger than 7.5 GeV and mans (1+) to be larger than 9 GeV. The coupling stren gth o f T to has been found to be l e s s than 2.53f to th e coupling by Columbiar-BNl and th e same lim it Is put at 6% by the HEBC group. As regards to L° production, Aachen-Yadova group £3.53 has reported 12^i~e+ type events C.p > 2 GeV/c) at PS energies where 'charm background i s only 4+2< These p~ e+ pairs are not associated with hadrons other than recoil protons. The small angles between th e muon and th e elec tro n make charm as an u n lik e ly source. However a neutral heavy lepton of mass » 2 GeV can explain the events reasonably well. SKAT group at Serpukhov [5.7l reported a^t“e+ event having a lifetim e (5-7)x10-12 sec (there is a visi ble gap of 4.8 mm between the ' f i vertex and the decay vertpx). la stly the BEBC wideband group (2.SJ in hydrogen has reported a 3 standard deviations btimp in n+ mass (fig .6.3) which has been supported, by the narrow band group in neon. All these heed, to' be verified before any further conclusion can be drawn., - 96 - 7. Beam dump ex p erim en t 'y-beams are obtained in the accelerator laboratories from decay s o f it and K. To Investigate any other sources of , i.e. from a parent with a shorter lifetim e, several beam dump experi ments were performed. The m odification to a s.taindard set up involves the introduction of m aterials immediately when the. secondaries are produced (see fig.7.1). it and K would interact rather, than decay, and the flux of the .conventional' type of y 1 s. .would be reduced by a factor of thousand or more. 7.1 Observation of prompt The Spark chamber group at Serpukhov ( 7 .ij observed 195 p. events and 45 electron type events. Prompt source was estimated by subtracting backgrounds from (1) a study of the density of the target material (2) the measured V flux as obtained, from o b se rv e d p. f lu x . The. mean v a lu e i s 12+10 w hich does h o t e x c lu d e a zero effect. This corresponds to = (0.72+0.66) • Q . 1 0 '5 In SPS, three groups (two bubble chamber and one counter) C7..2J s im u lta n e o u s ly -lid beam dump ex p erim en t w ith an i n te g r a te d 1 7 proton intensity of 3.5x10 on the target. The first observatioi was.the fact that the relative number of e-type neutrino, inter action has .increased significantly from the conventional runs. — + Expected ratio and •§— events from K, , E decays to be 0.06 }x and 0.1 respectively whereas the BEBC group observed the ratios as 11/29 and 4/5 respectively. The CUES group saw a sharp increase in the NC/CC ratio which can be consistent with the - ST - earlier measurement, only if one assumes a significant increase in t h e V Q( A-'g) flux. The results are tabulated in table 7.1... Also there is a significant difference between the expected (.14-6+0.15) and the observed (.22+0.2) ratio of pi + to y T e v e n ts . • Absolute event rates are predicted using the particle production spectrum from a thermodynamic model. This leads to an equal amount of prompt v> » V , v , v in the source. There is an extra r ■ r . __ - piece of information coming from the narrow band run with v where an excess of Vg type events were observed. This experi ment was carried out With the proton hitting the Be-target at • ' 15 arad (in the-other beam dump, proton hits a Cu target at 0 mrad). The prompt flux is better expressed as ^p/n ratio and shown in figure 7.2 together with other observations regarding prompt lepton production in hadron collision. These prompt j/'s could be explained in terms of charmed particle production and the cross-section needed to explain the observed event rates , vary from 20 to 400 pib (such wide variation is due to - the uncertainity in the production mechanism). 7.2 .. Universality in weak current The eVents observed in BSBC and G-argamelle also provide some indirect evidence on the issue of yU-e universality in neutral current interactions. From the observed v ( ^ ) charged r . r. current events, one expects to see 16 neutral current.events whereas the observed number is 26. The observed number of e~ and e+ events would product an excess of 8, if.^i-e universality is valid. Thus the data not only gives evidence for neutral current events induced by and v e but also suggest the strength to * 98 - be compatible with p-e universality. 8 . Summary The important "results are summarised below: (1) The charged current studies have been refined to understand the nucleonic structure. Together with ed and pp deep inelastic scattering data, these studies establish a scale . breaking in these scatterings. This breaking has been, attributed to the 1st order correction of QCD and the quantitative checks seem to agree with the theory, rather well. (2) Data from a diverging set of experiments have been used to study the coupling constant in neutral current interaction. The coupling constants agree reasonably well with the SU(2 )xU(1) model due to Weinberg and Salam. Parity violating effect in e-d scattering has been experimentally demonstrated. There is some evidence of ^i-e universality in neutral current interaction. (3) The hadronic 'distribution hats been studied in the framework of Quark Parton model. The fragmentation functions aeem to agree fairly well with the theoretical expectation. However one finds the effect of first order QCD corrections to be important in the transverse momentum distributions. (4) Unlike charge dilepton events are well understood in light of the DIM model with charm. Trilepton events can be - accounted for from the production at the hadron.vertex’in terms of known quarks (+ some internal bremstrahlung of the leading - 93* - muon). The strange sea evaluated from the analyses indicates that the sea is not SU(3) symmetric. (5) There' is evidence of production of charmed particles in v interaction. However the evidence for heavy leptons is not that conclusive. (6) There is evidence of a prompt source of y ’s in hadron- hadron collision. This prompt source could very well be the produced charmed particles. ftf-Tmowledgernent: I am .thankful to a number o f persons fo r preparing this talk. It is impossible'to mention them all by name, nevertheless I would like to-mention Dr J. Muivey, Dr K.W.J. Barn ham and Mr P. Mitra for their kind help in this r e s p e c t. * - toe - Reference [2.1] M.M. Bleed eft aa,,- Sbys, Sett. 1g (£4> 2S1 A, Otteen Seeomrtela eft al,, Buov. Cto, 5&S ( 67 ) 927 H» Hold®? eft65 L., Knov, 0#i* 52. ^68 ) 39B It, S. SttCtas a# al,, Btyrs, Rev* Sett. 33 (69) 1014 $, Bugaev eft al., 8 »sv. Cjja, Lett. £ (69) 699 S. Bonaefttl aft * 1.. maoV. Cfea. ?8 A (to) 260 Papers submitted Topio«tt Socfenettce on ^Pbyeiee-^Otford19 ®)( {Ml J- M1 e* 90Li» $h5». fie*. Eeftt. £2 (18 ) 1012 C2*S 3. Adler, Bby#, Re*. £)& 75( ) S544 {2.4| V,B. Barnes eft & 1918 ) z $•% P» Boseetti 9* al*„ Ptiya. Sett, 2g| (77) 275 B-.G, Banish eft al,, Pbye, Rev, Sett.. 53 (77 ) 1595 S.d. Bariett eft si., Phy». Setts* jg£B (77 ) 291 M. Holder eft at;* Paper submitted to Topical Coat, on V Physics - Oxford (78 ) end Tokyo 'Conference 78 ( ) B.3. Baranov eft at.. Paper submitted to Tokyo Conference (78 > A.B. -’yaaff'stiratan eft gl., Pbys. Sett. 76 B (78 ) 238 (2.$ P. Seuilli, Pro®, of Topical Conf. on V ptiys. Oxfbrd 78 ( ) g .1| M, Hold®: eft al., Pfeys, Sett. (77 ) 577 ...... - B.C. BariSit eft al., Ways. Rev. Sett. £0 (78 ) 1414 52.<§ K. Tlttel - Talk presented to Tokyo Conf.78 () £2.1(3 P.O. Bosett1 et al., Oxford University Preprint 16/78 £.13 E.M. Riordian et al., SIX-PUB- 1634 (75 ) H.S. Anderson eft aT., Phya. Rev. Sett. 3§, (77 ) 1450 H.L. Anderson et al., Phys. Rev. Lett. ^ (76 ) 1422 - 101 - £2.12} J.M.' Cornwall and R.E. Norton Phys. Rev. 177 ( 69 ) 2584 {2.13)0. Nachtm.ann Nucl. Phys. B65 (75) 237 0. Nachtnann Nucl. Ph.ys. B78 (74) 455 (2.14} B.C. Cross and F. Wliczek PhyS.Rev. to (73) 3633 . D.O. Cross and F. Wjjczek Phys. Rev. IQ. (74) 980 8. Ceotgi aSd H.P. Politzer Phys. Rev. Bg, (74) 416 (2.1$ Bardeen et a l., FNAl 78-42 THY 13.13 F.J. Hasert et al., Phys. Lett. 468 (73) 138 £3 .5 S. Weinberg Phys. Rev. L e tt. 15. (67) 1264 . . S. Weinberg' Phys. Rev. Djj (72) 1412 A. Salan 8tb Nobel Symposium (Stockholm 69) 367 [>.3jf P*Q» Hbhg dtod J.J. Sakurai Phys. L ett. 63B (76) 2195 [3.§ J. Blietsehau et al., Phys. Lett. £2B (78) 232 H. F a ls s n e r e t al.» Phys. R ev. L e t t . 41 (7 8 ) 21.3 P. Alibran et al.„ Phys. Lett. 74B (78) 422 0. Ball ay et a l., Pt$ye, Rev. Lett. Jg. (77) 62 P. A lib ra n e t a l . , CERN/BP/PHYS 78r.6 (1978) ' F. Reines et al., Phys. Rev. Lett. (76) 315 £3.5} C. Balt ay Talk given to Tokyo C -nf.' (’’h) (3.63 J. Blietsohcm "et a l., Nucl. Phys. B118 (77). 218 F.5. Herrit et al., Phys. Rev. D17 (78) 2189 P. Wanderer et .al., HPV7F 77-1 (July 77) M. Holder et al., Phys. Lett. 72B (77) 254 P.O. Bosetti et al., Phys. Lett. 76B (78). 505 [3.7] H. Deden et al., Aachen Preprint PITH.i-103 (78) [3.8/ F..Harris et al., Phys. Rev. Lett. gg (77) 437 H. Derrick et al., Phys. Rev. D18 (78) 7 J. Marriner LBL-6438 (77) - 102 [3*9\ W. lee et a l., Phys. Rev. Lett. 32 ('76) 186 D. Cline et al., Phys. Rev. Lett. 3X (76) 252 D. Cline et.al., Phys. Rev. Lett. 3X.(76) 646 M.-Pohl et al., Phya. "Lett. 22B (78) 489 (3«1 <3 W. K renz e t a l . , N u cl. P h y s. Bj 55" (7 8 ) 45 " D. Erriques et 'al., Phys. Lett. 75B (78) 550 W. Lee et nl., Phys. Rev. Lett..J8 (77) 202 (j.lflH . kluttig et al.; Phya. Lett. 212 (77) 446 [3.15) L.P. Abbott and R.M. Barnett Phya. Rev. Lett., £0 (78) 1303 L, F, A bbott and R.M. B a r n e tt SLAC-PUB-21 36 [3.13]L.L. Lewis et al., Phys. Rev. Lett. 32. (77) 795 P.E.G. Baird etal.> Phya. Rev. Lett. 32 (77) 798 N„ Fortson Proc."of V-78 Conf. (Purdue 78) L.M. Barlov et al., JETP Lett 26 (78) 379 (also Tokyo Conf. 1978) [3.15 °.Y* Prescott et al., Phys. Lett. 222 (78) 347 (4.1} J. .Bell et al., Michigan Univ. Preprint UMBC 78-6 A. V ayaki e t a l . , CERN/EP/PHYS 78-28 P.C. Bossctti et al., Oxford Preprint 58/78 V. Stenger Oxford Preprint 59/78 M. Derrick et al., Phys. Rev. D17 (78) 1 ^4.3 R.P. Feynman and R.D. Field Phys. Rev. D15 (77) 2590 (4.3j H. Georgi and M. Machacek Phys. Rev. D15 (77) 1416 |4.4] Sterman and S. Weinberg Phys. Rev. 52 (74) 3391 • * (4.5 Papers submitted" to Oxford Conference (78) Also see [2.63 / e .... C?.l 4. Benvenuti et al., Phys. Rev. Lett. 34 (75) 419 - 103 - [5.2) A. Benvenuti et al.,. Phys. Rev. .Lett. (78) 1204 B.C. Bsrish et al., Phys; Rev. Lett. J6 (76) 939 M. Holder et al., Phys. Lett. 625 (77) 377 J. BlietsohaU et ol., Phys. Lett; 533 (f5) 361 J. Blietschau et ol., Phya, Lett. 60S (76) 207 P.O. Bosetti' et al., Phys. Rev. Lett. J8 (77) 1248 O.E. Erriquez.et al., Phys. Lett.. 77B (78) 227 P.O. Boaetti et al,, Phys. Lett. £2§ (78) 380 . J. V.ankrogh et al., .Phys. Rev. Lett. ^8 (77) 1248 £5>3 Bais and S. Trieman Phys. Rev. Lett. 25, (75). 1206 [5.4) B.C. Barish et al., Phys, Rev. Lett. 28 (77) 577- [5 .5 A. Benvenuti. et al., Phys.,,Rev. Lett. 40 (78) 488 T. Hansl. et al., Phys.- Lett. 77B (78) 114 6 -5 C. Baltay et al.," BHL-24663 submitted to V-78 conference |5.7} D.S. Baranov Serpukov preprint I EVE 77-30 (77) [5.8) M. Holder et al., Phys. L ett.. 75B (78) 105 ,'R.J. Loveless et.al., Phys. Lett. 78B (78) 505 [6. 1J M. .Holder et al., Phys. Lett. 74B (.78) 277 [7.l} A. . Soloviev Prc c. of 77 Int. Symp.. on lepton and Photon Interaction at high energies [7.5il P..Alibran et.n l,, Phys. Letts. 74B (73) -134 . T. Hansl et al., Phya. Letts. 243 (78) 139 P.O. B0setti et al., Phys. Lett. J4B (78) 143 H. Wacksmutti CERH/EP/PHYS 78-29 - 104 - Table 1.1 Electronic•Detector Bubble Chamber. Target mass goes up to Target mass is typically 10-2C 1000 to n s tons-so event rates are down. * by a factor of 50 p identification is * . It heeds an EMI for unbiased^ excellent (from range) identification Neutral component of Part of the neutral shower is hadron shower is well invisible and fudging is m easured n e c e s s a ry It is blind to details It is excellent for details of the shower of the shower It has no electron, V° •. Electron, V° identifications detection capability are very gobd Angular coverage is not 4 it a n g u la r a c c e p ta n c e always complete - T05 T ab le 2.1 5 S Canment - ■ Q + CDHS 0 .1 2 + .0 0 2 0 .0 4 * 0 .0 2 , Dileptori data 0 .0 2 + 0 .0 0 7 BEBC 0 .1 1 + 0 . 03 - - ■ HPWFOR 0 .1 4 + 0 .0 3 0 .04+ 0 .0 1 5 Col-BNX - 0.015+ 0.01 Dilepton data A verage 0 .1 3 + 0 .0 2 0.02+ 0.01 T ab le 2 .2 O bserved QCD QCD- . s lo p e P r e d ic t Prediction io n ( s c a l a r ( v e c to r g lu o n ) g lu o n ) d ln'M 3(JJ=i6)/d ln M3(N=4) 1.29+ 0.06 1.290 • 1 .0 6 d In M ^N ^/d In M3(N=3) 1 .5 0 + 0 .0 8 1.456 . • i .1 2 - ‘ d In M3(S=7)/d In M3(N=3) 1..84+0.20 1 .7 6 0 1.0 9 - - - 106 - T a b le 3.1 E xperim ent R ea c tio n C b arg ed E v en ts Back Cross-section c u r r e n t o b s e r ground lO -4 2 ^ cm2 sam ple ved G arg am elle 1 0 .3+ 0.1 < 3 (CERN-PS) v ’ - y ~ Gargamelle . -3 0.4+ 0.1 1 o'*2 *’1 (CERN PS) -Of. 9 Aactaen- 32 ' 21 1 . 1+ 0.6 P adova v p e~-~yie~ (CERN-PS.) Aach en - T7 7 . 4+ 1 .0 2.2+ 1.C P adova (CERN-PS) G arg am elle 41000 9 0 .4 + 0 .4 (CERN-SPS) vF e~ ~ y ~ 4 ,3 - l l 5 t0 G arg am elle 4000 ’ , "0 < 3 .3 (CERN-SPS) BEBC 7500 1 0 .4 + 0 .2 (CERN-SPS) < 3 ,5 C olum bia- v e- —V e 100000 11 0 .7 1 0 .7 . 1 .8 + 0 .8 BNL ( FNAL)' ? ? FNAL-MICH-- 6300 0 : < 2 .9 IHEP-ITEP ( FNA1) 180Q MW (.87+25)6-^ '' V ~ 5e e’ f i s s i o n [_1.5 O arg a- 1-10 1 0 .2 5 + 0 . 04 0 .5 6 + 0 .0 3 0.26+0404■ 0.3 9 + 0 .0 6 m e lle , CERN BUI 1-10 0 .4 0 .25+ 0.05 7 'BO HP WE, 30-200 -"4 ' 0 .2 8 + 0 .0 5 0 .3 9 + 0 .1 0 0 .3 0 + 0 .1 0 Oi 38+0.09 FNAL 3ITFR,. 30-300 12 0 .28+ 0. 03 0.35+0.11 0 .2 7 + 0 .0 2 0 .40+ 0.08 FNAL ODHS, 30-200 12 0.293+ 0.01 <0.3510.03 0.295+ 0.01 0 .3 4 + 0 .0 3 CERN BEBC 30-200 15 0 .3 2 + 0 .0 3 0 .3 9 + 0 .0 7 N arrow ban d - CERN ■ 15'BC, 10-100 10 0 .35+ 0.06 FNAL i— —— Table 3.3' R*1 = 6^( v -* ^ ) | Berkley-Hawaii-Michigan ! 6.48+0.17 ■ V ' ■ ' 1 -p _ grP( jT _ V ) AML-3 arn eg ie M ellon- 0.4-2+0.1 3 Purdue (2-) LEL-ENAL 1.31+ 0.38 - > 0 8 - T a b le '3 .4 - > p -..V E x p e ri- v > P m ent Bv exits : Bgtck— vu p - vu p E v en ts Back vu P - v u p o b s e r ;ground o b s e r ground ved y - r ? ved VpP — p +n EPS 255 88. 0 .11+ 0.02: . 69 28 0.19+0,05. ( o ld HPW) CIR : : 71 30 0 .20+ 0.06 A acben- 155 110 0.1 o+o. 03 Padova G a r g a - .. .1 0 0 . : 62. 0.12+ 0.06 m e lle (PS ) - 109 - T ab le 3 .5 E x p erim en t Ratio measured Experimental results (VX 1t°) CIR/Aachen Padova 0 .21+ 0.07 2(ji~ X k°) VX it0 G argam elle 0 .4 6 + 0 .0 7 2 {p + X it°) Vn it+ AM 12' deuterium 0 .1 3 + 0 .0 6 ^"*PTC+ V 131t° ■ 0.40+0.22- p~plt+ Vpit- 0 .1 2 + 0 .0 4 ^ ”P " + Vnit0 +\> nit° Gargamelle propane 0 .4 5 + 0 .0 8 2(^T pit°) — o — o • VT3lt + VnTt 0.57+ 0.11 ’ 2(^i+n a°) V.. VpTtU 0.56+0.10 • jT p it0 1 J o . vnu 0.34+ 0.09 ^ " p it0 • Vmt~ - 0 j 0.45+0.13 ^ pit v n it+ 0 .34+ 0.07 - 0 - 110 - Table 3.6 Coupling constant Evaluation by Abbott Weinberg Salam and. B a rn e tt s i n 2^ 1 /4 g V 0 .0 + 0 .1 0 .0 g A -0.55+0.1 . - 0 .5 UL 0 .3 5 + 0 .0 7 0 .3 3 dL -0 .4 0 + 0 .0 7 -0 .4 2 UR -0 .1 9 + 0 .0 6 - 0 .1 7 % 0 .0 +0.11 0 .0 8 T ab le 3 .7 Xin ran , WS-prediction Experimental value S e a ttle 876 - 23x 10-8 .. (-.5 . + 1 .7 )x10-8 O xford. 648 -3 0 x 1 0-8 (-5.0+ 1.6)x10-8 . Novosobirsk 6 48 . -3 0 x 1 0 -8 (-49.5+5) x 10-8 - 111 - Table 5.1 Experiment.. Beam T a rg e t O bserved O bser r a t e (%) FfieV) e v e n ts v ed v° i 1* HP WE V 350 l i q 160 p~p-+ - (0.40+0.08) s c i n t i llato r, lro b f i l t e r V 50 l i q 90 p +p~ (0.27+0.09) s c i n t i l l a t o r iro n f i l t e r 0ITFR V 100 S te e l 67 p~p+ - .1 V 100 S te e l . 28 p * p ~ — 1 CDHS V 100 Ir o n 257 p~p+ - 0.49 V 85 Iro n 58 p y . -■ -0 .3 9 G arg am elle ■ V 2-10 Freon 14 ^ir e + 3 0.3 1 + 0 .1 3 Wis-CERN- V 30 21X Ne-H 17 )i~ e+ 11 0 .8 + 0 .3 FNAL Col-BN I 30 64% Ne-H 204 u ~ e+ 43 0 .5+ 0.15 L B L -S eat- V 30 64%- Ne-H 1 p~ e+ . 1 0 .3 4 + 0 .2 3 H aw ali - 0 .1 3 . + — 0 15+0 - 14- - L B L -S eat- V 30 .64% Ne-H 4 p e 2 -0 .0 8 H aw aii . FNAl-Hawaii- • y 30 64% Ne-H 9 ^ ” e + LBL FNA1-HEP- V 30 64% Ne-H 6 p~ e+ 1 0.21 ITEP-Mich - FNAL-HEP- V 30 21% Ne-H <1 p +e~ 0 <0.5% ITEP-M ich FNAL-HEP- ' y 30 •/ 64% Ne-H 12 /p +e~ 7 . 0.22+0.07 ITEP-Mich ' BEBC ' y 75 ' 64% Ne-H’ 5 p ~ e ++ ' 2 0 .7 + 0 .3 BEBC 1 y 75 64% Ne-H 11 p 'p •6 0 .8 + 0 .3 BEBC y 30 64% Ne-H 21 p ~ e + 6 0.41+ 0.01 C-W-B-LB1 y 50 45% Ne-H 40 p~p+ 5 0.43+ 0.1 G arg am elle V 30 . Freon 70 p p 8 0.62+ 0.18 skat V 2-30 Freon 8 p e 1 0 .7 + 0 .4 Table 5.2 Gol-BNL CDHS HPWF' V .. . . HPWF V b-Quark/Valence Quark 3+ 2/ 5 + 2 / (9 .9 + 3 .5 ) (6 .6 + 6 .1 ) T ab le 5 .3 E xperim ent Beam Pp ^ t W e n t a o b serv ed (BG) ... 6(3 p ) /6 ( 1 u ) 4 A ll E B> 120 GeV CDHS WBB 4 .5 GeV/c 76 (6 ) 4 ( 6 .6 ) (3.0+0.4)x10~^ (1 1 + 2 .5 ) x 10~5 CDHS ‘ WBB 4 .5 GeV/c - • 6 (2.4+1 )x10~^ , HPWFOR' • . WBB 2 GeV/c 49 2 (6+2)x1:0-5 (12+ 5)x10-5 T ab le 5 .4 E xperim ent Beam ty p e in V Background r a t i o ln ^ 1 r a t i o ... r r CDHS • , Narrow.band 47 30 8 + 5 / 9 CDHS Wide band 289 200 < 7 / 23. < 1 0 / HPWFOR- Wide band 38 18 12 + 5 / 2 T able 5 .5 E^G eV ) Group,. • liver.t type ’ PX1(GeV/c) P12(G'eV/lc) P13( GeV /c; P14(6 eV /c) E v iS(GeV) — + c— in in cooo CDHS 9 11 - . 45 ' ". 9 71 HPWFOR n Y p .44 60 4. ■ 3 289 BFHSW ji+e“ e e~K°7Y .22 2 .3 2 .0 0 .9 32 Table 7.1 BEBC . • •’ CDHSB G argam elle e /f- 6+/ h + NO/CO (e+ + e^)/ (/i+ + /U~) Eh >20 GeV Evis >1° GeV : W 20 Ev is> 5 ° W 10 6eV 0 mr 0 .0 7 0.09 0 .3 0.16 0.12 0.0 7 E xpected 15 mr 0.1 6 0 mr 0 .3 7 0 .8 0 0.86+ 0.08 0.0 2 + 0 .0 2 0.19+ 0.02 0 .5 6 O bserved 15 mr 0.6 7 - 114 Figure Captions 1.1 E x p e rim e n ta l s e t up a t SPS 1.2 Deep inelastic scattering (see text) 2.1 Evaluation of from quasielastic CC' v scattering 2.2" Charge current cross-section ratio on neutron aM protoil t a r g e t s . • ( - ) (-) 2.3 Cross-section for j) N ^ 1"X- as, a function of V energy 2.4 • Ratio of; V to ^ CC cross-section as a function of en erg y 2.5 Piot. Of • • - p • 2.9 Test of callan vross relation in x and Q Bins 2 2.10 Structure function integrals as a function of Q 2.11 Plot of log of F^ Nachtmann moments for various N-values 2 - 2.12 Q dependence of F^ Nachtmann moments 3.1 Evaluation of gA and gy from V-e elastic scattering data 3.2 pit0 effective mass plot in the reaction vp -* V p^° 3.3 Experimental set up for polarised e-d scattering experiment 2 3.4 Evaluation of sin ©w from various measurements 4.1 Average hadron charge m ultiplicities in ff and bins 4.2 Average hadron charge multiplicity as a function of W (with a cut in z) 4.3 Fragmentation function distribution from various experiments 4.4 z-distribution of fastest positive and negative hadrons - TT5 - A»5 "Charge p a r tic le correlation for negative, anil p o sitiv e p a r tic le s .4*6 .Pj distribution of hadrons in charge current events 2 P 4 . 7 4»8.',. 4.9 Probability of 3-jet production in CC V. interaction 4.10 ,; V°. m ltip licity as a function of x in CC v interaction. 5.1' - Various mechanisms for dilepton production. • 5.2 Dilepton rates as a function of V-energy 5.3 x and y distribution for the leading lepton in dilepton ssCmple 5.4 .. Various mechanisms of trimuon production 5.5 Trimuon rate as a function of ^-energy 5.6 Effective mass of two non leading muons in trimuon sample . 5.7 >pj distribution of . the non leading muons with respect to q 5.8 Azimuthal distribution of the nonleading muons with respect to the leading muon 6.1 Kitx mass distribution in CC sample of.Col-BNL group 6.2 Limits on heavy.lepton mass from-CDHSB group 6.3 . mass distribution for;the tv.o BEBC groups 7.1 Beam dump experimental set up at 3PS 7.2 -Prompt lepton to n ratio observed in various experiments 116 - imuMip Mur iumi hadron (m ass* W N (mass= m) Energy=EH) " (G eV /c8) b e 1 - 117 - y a . • - C CSPSI 6C E 8 TP F U A (FN PR 1T C * v GGM • HPWF o C1TFR o CDHS o o o o o E GeV FIG 2/ as °O0o^ 0 *• !02 ’ e 4* v v CD • A SKAT o o Am 0 P'ANL * *» • ■ CDHS < oo GGM/BEBC 005 * 15 FNAL e e o -a • o ► " ITEMHEP o x m *nox ci 01 _j_ o wO^tflaj-n 002 1 100 10 E GeV FIG 25 E • 30-90 G«V £ • 90-100 GeV . I to) lb) * O 05 O' 00 0-2 0-4 06 0*8 1-0 0 0 0 2 0-4 0*6 0-6 t y . FIG. 2*8 * 0 5 ri5 M 0-4 SO 900 0 3 * 00 0-2 0*4 0-6 0 8 10 K FIG. 2 8 1C) • Leg el momtM • IUMIQUI |0 6 o i FIG. 3 1 20 X 1-09 1-29 MASS (pv*) (OeV/c8) FIG. 3 2 121 - SEAM MONl TORS I CURRENT • ; ENERGY 1 POSITION a n g l e ______. *3qAs SOURCE}1 U COMPUTER TO ELECTRONICS TO ELECTRONICS F ig. 3.3 o , F IG .3 -4 w-e-to GeV W-6-8 GeV 4 :‘f"1—*r—4---- W *4-6G #V ;y~*~j-- 3 c W«3-4G eV 2 4 ■W-2*»3GeV 9 2 « * - * « 2 4 8 l« 92 6 4 Q* GeV8 FIG. 4 ‘l • Ivw lth Z 9*2 o h'wlth Z >*2 5 IO per per event O-l W(GeV) L - 123 - ■ ‘■ps A V •2-1 A ISI or V FIG. 4 3 001 0001 o 2 4 6 8 10 Pf (CeV/O2 . FIG 4.6 2/N z> 0.2 1/ N 0.8 ® QCD - LP5 all z 0.2 ,2 FIG 4J - 124 - 0 6 (A) 0 3 0 (B) (O . W > 6 G fV /0 - L P S - L P S — L P S 0 4 0 20 » -.f.0CD v> blb V 0*2 0 10 01 001 2 0 20 0 8 1*0 W. GeV/C FIG . 4-8 *b FIG. 4 1 0 125 - Tjhedrons J hadrons (E) FIG. 5 I CDHS O-Ol COJ-BNL 0 0 0 5 0-01 00 0 0 0 5 0 0 0-0 50 100 150 200 E (GeV) FIG. 5 2 126 HPWF COL-BNL 100 100 60 8 0 60 60 4 0 4 0 20 0-9 i-0 0 0-9 10 o 0 5 10 0 0-5 X VIS Yvis FIG 3-3 (O) hadron h o d ro n (B) r (4£) • MPWF o COHS -5 5 0 100 ISO 2 0 0 Evig(Gev) FIG, 5-5 (CeV/c) — HMU 20 4 0 9 0 10 20 0 0 I 2 3 4 0 6 0 120 180 Moss (M2 M3 r (GeV) ( degrees) . FIG. 5 6 FIG. S B i j »$3 ai P» q X NUMBER OF EVENTS EXPECTED - 831 - K B C GGM P, > GtV/c SPS — ,0- beam rf Yvls > 0 -5 (wb) r COS 0 > - 0 8 CDHS beam ' FIG 7.1' OS 10 IS 20 25 3 0 3 5 2 10 M assI/T 7r*)(GeV/Cz) 30 NB Ne P* > 2 GeV/c 10 20 VIS>0 S COS0>-O-8 5 10 6 10 IS 2 0 2 5 3 0 10 100 200 300 MASS(>i-ir*)( G eV /C 2 ) 0 E; GeV FIG. 6-3 FIG 7.2 ■ - 130 - BISCUSSIOH Probir Roy: QCD has a specific prediction for the Callan-Gross relation, at finite Q^, i.e. R a S ^ « Is there any v ■ - Q - verification of that in neutrino scattering? S. Banerjee: Violation of Callao-Cross relation gives rise to a linear term in y in the differential cross-section. Due to biases in the experiments, it is hard to obtain a reliable y-distribution. So the validation of Callan-=Gross relation can be tested only within a large uncertainity. As fa r as I know, no experiment has y e t managed to obtain p data senative enough to test the Q dependence of the v io la tio n . K.V.l. Sarmas"1) Evidence for Callan-Gross relation from V data assume the validity of charge symmetry, which itse lf may be violated. Perhaps the best evidence f*r this is /•2XF, - j j ' = 0.25+0.1 (g iv en in the recen t review o f Hand) coming from electron scattering experiments. 2) Regarding the observed parity violation in the e d experiment it is difficult to associate it unambiguously to neutral current or to electromagnetic interactions. What y all we can say for the present is that parity violation is observed in the scattering of ed experiment. v - 151 - I. Das: Ion presented charged current cross-section data for the proton and neutron targets separately. These would give the integrated distribution functions for the u- and d-quarks. I suppose these numbers are consistent with what one would obtain from the electro-production experiments. S. Banerjee: In principle, one could test that.I am sorry, I do not know how w ell th ese numbers t a l l y w ith the electroproduction data. and <1-T> distribution.‘One see that a lim ited pj Monte Carlo cannot describe the data. Fig.4.8(c) shows the thrust distribution for W > 6 GeV. Again, t h e .d a t a d i f f e r from th e LPS m odel. The.QCD curve with correction for the hadronization of the gluon agrees remarkably well with the experimental data.#, <1-T> and distributions for the fragmented-hadrons