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7 7 INSTITUTE of THEORETICAL and EXPERIMENTAL PHYSICS Aeasratyan, Avfedotov, RA.Gorifchev, SP Krufchinin

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7 7 INSTITUTE of THEORETICAL and EXPERIMENTAL PHYSICS Aeasratyan, Avfedotov, RA.Gorifchev, SP Krufchinin ITEP 86-77 INSTITUTE OF THEORETICAL AND EXPERIMENTAL PHYSICS A.E.Asratyan, A.V.Fedotov, RA.Gorifchev, S.P. Krufchinin, M.A.Kubantsev, I.V.Makhlueva, V.I.Shekelyan, V.G.Shevchenko, V.V.Ammosov*} V.S.Burtovoy*} A.G.Denisov**, G.S.Gapienkox' x x V.A.Gapienko ) V.I.Klyukhin*'. V.I.Koreshev ^t x x x P.V.Pitukhin ), V.I.Sirotenko ^, E.A.SIobodyuk ^f V.G.Zae«zx) OBSERVATION OF THE CHARMED STRANGE PSEUDOVECTOR MESON CASCADE RADIATIVE DECAY Preprint Moscow -ATOMINFORM-1986 Institute for High Energy Phisics, Serpukhov, USSR У.'.л 533.I7.J M-I6 0В5ВПТАТЮИ О? ТЯВ СНАИШ) ЗТ1АН0В РЗВОЮГВСФОЖ ПЗОЯ CA3CADB RADlAfTO DKATt Preprint ГТВ? 86-77/ A.S.Aar»tyan, A.T.FtdotOT, F.A.OoritchOT *t al.t I АПЖтУОШ, 1Э86 - 8p. Abstract The antlneutrloo production and eaaeada radiatir* deoaj of the chanted strange paavdovaotor neaon are oba#rr«d. The paeudovaetor and raetor P aeaon тлвввш are aaaeured to b» (2547^60) Мет and (2123*15) Пат, raapeetiraly. - 2, raf. - 5 (6) Центральны» иауио-исстодомтвльскМ шнстшуг «нформмм я техмпю- акономическнх исслвоовмм* по атомной науке • технике (ЦНИИатомнмформ#,1966 The weak transitions wi -> P^i, Pgi with subsequent off- nueleon scattering of the vector (Py) or pseudovector (Fj[) charmed strange meson might account for the bulk of the F(el) neutrinoprbduction £i-2j. The experimental observation of the TOD-produeed P*" radiative decays P^~ -> ^P~ was indeed recen- ly reported by our group £3] (almost simultaneously with the •*•" results J4J). Reported in the present paper is the search for the radiative decays of the pseudorector (cs) mesons produ- ced in v H interactions. Analysed are the antineutrino data collected with the Fer- mi lab 15-ft bubble chamber filled with the heavy neon-hydrogen mix (the data as well as the charged current sample are descri- bed at some length In JVJ). The metho' employed is the reconstruction of the ground- state F~(1970) meson by its hadronic decay products and analysis of the gamma momentum spectrum in the f rest frame. The "recon- structed" T~ should be understood here as the collection of par- ticles with the invariant mass close to that of the 7(1970)t the par tides coming from the primary interaction vertex (the 7 is too short-lived to be observed as a track in the bubble chamber). Towards the P reconstruction, we try the following hadro- nio decay nodes : Г" -> У -#. KpT, Kp'rt0, ЪрГ-п*тГ, K§K*tr-ir~ 2 To clarify the procedure, a few remarks are necessary : i the pion and kaon masse* are arbitrarily ascribed to the charged track* (not identified as protons or electrons) ; ii to isolate the <P -> X*t~ decays, we select the X*K~palrs with mass in the interral 1020 - 15 Мет ( ~ 2 calculated standard deviations) ; iii in the case of У -• ^P X, 4? -* КИС? we reconstruct the *?> four-momentum, simply multiplying that of Kg by a factor mC?)/m(K|) (the к£ is not registered in the chamber). This approximate method is justified by the smallness of the 4» -> K^K° phase space. The induced "kinematic" uncertainty of the ? mass reconstruction is calculated to be—95t 75, and 50 Мет for the decay channels ?"-* *?*!'» ЯРтГп0, and , respeetirely ; IT to reconstruct the neutral pions, we select gamma pairs with шааь in the interval 135-20 Мет (in accordance with the width of the «° peak on the overall m~y швав plot}. The gas- mas that remain are called "odd". The decay sy&tem mass m is required to lie within one calculated standard deviation 4 of the ?(1970) mass: Дв < 4. The ralue of 6 is calculated individually for each systea by varying the momenta and angles of all the particles within the measure- ment errors (the kinematic uncertainty associated with 9 -& is also included). The typical o* value is ~100 ler for *PI, 9 -+ KgKj and *-50 Мет for the rest of the listed decay channels. 3 In the rec one true ted F~ meson rest frame we p3ot the mo- menta Ei of the odd (surviving the T5° rejection procedure) gam- mas employing two additional selection criteria. The first (on the eTent level) ie the constraint on the square of the four- momentum transferred from leptons to hadrons: Q < 2 Gev . The motivation ie that the VXD mechanism effectively cuts Q at the level of the order of (pseudo)vector meson mass squared. The second selection oriterium (on the combination level; is the cut * > .7 on the fractional visible hadronlc energy carried by th€ ?£f system. The latter is oriented towards the P»K -> T*H transitions with snail inelasticity. Plotted in Pig. la are the odd gamma momenta in the recon- structed P~ frame. Apart fro» en enhancement near 150 Mev sig- nalling the Щ~ -> У?* decay £3-*J, a cluster is observed at 400-600 Mev. To estiaate the background, w» plot s i a similar distribution» but with the shifted mass value, 1. e. 1.5*: Дш/о'^г.5 (••• M.g. 1b) ; 11 a similar distribution, but with the system charge sign inverted t *Pn+, «to. (ее* Pig. 1e). Comparison with the background wouldn't lead to any reliable positive Interpretation of the 400-600 Mev cluster In Pig. 1a. The two-dimensional plot in the (El» , Sin) plan* (by con- vention, BL. > E&9 ) for events with two odd gammas contribtt- ting to the one-dimensional distribution in Pig. la proves more Informative. In ths area 400* El, < 600 Mev, 100<iE» < 200 Xev an isolated group is observed which consists of 5 "cascade* 4 erenta. The risible width of the signal in both variables la consistent with the experimental resolution (the ganaa momentum measurement error is •~2O56). Of the two-dimensional background plots corresponding to the one-dimensional distributions of Pig. 1b and Tig. 1c, the former consists of a single point (EL, » 123 Мет, Ei2 - 67 Mev), while the latter is completely empty. We conclude that the back- ground in the area- 400-C S1^ < 600 Мет, 100<Etg < 200 Мет is small. Some characteristics of the five "cascade" events are lis- ted below (all quantities in Mev, the denotations ^_ and <&oo stand for T -^X^K" and <F — K|K° , respectively): Decay m- $ 3lv> ^jTiP 1994-40 ~?96 447 2157 2549 ^jTi^rT 1946-26 193 486 2154 2630 <5^тг~-п+тт" 1961^17 131 427 2097 2489 «S^ITVH" 1925-125 165 580 2129 2632 КрГп*тГ 1958^24 111 418 2078 2436 The moat likely interpretation of these events is the cas- cade radiative decay PJ" -* ^*у~» Pf" -* fe*" of *he Peewio" vector (cs) meson VHS-produeed in ТдЯ interactions; They allow for a simultaneous measurement of both the vector and pseudorec- 'Had It been an orbitally-excited rector (oa) state (and not the pseudovector one)» ita radiative decays would be grossly orershadowed by the strong t-war» IX channel (for шааааа отег - 2360 Mev). 5 tor BUMI t л(Ц) • (2547 * 64» Мет , ш(Ц) • (2123 * 15) Мет • * The reported я(?$) ralue agree* well with our previous measure- ment of 2106&18 Мет [у\, лш well •• the 1RGU3 and the T?C •*•" With m(PJJ) > 2500 Мет, one Bight expect the TJ radlatlTe decays to Ъе OTerwheleed by the strong a-ware D*X ohaaael. There- fore, our data taken aa a «hole indicate that the lowest pseudo- vector (ce) state lies just below the 0«K threshold (^2500 Мет). We thank the physicists from ГезжИаЪ and the Unlrereity of Miohigan for their contribution to the Initial stage of the experiment. Helpful discussions with M* A» Shifnan are grateful- ly acknowledged. &. >w Mg.1 Th* odd gum e«nt«r>-of-ataa «onwntrm epeott» for т *) «yetm* of rl^it elgB with ^•/6/<1.j Ъ) ariratmw of right sign with 1.5 < .Да/о* ^ 2.5 j o) ejatvmm of wrong eiga with Дш/& < 1. ?i«.2 The two-dimensional SJ, - B^ plot for «rente with two gammas contributing to the one-dieeneional tion in Pig. 1a. 8 EBFBHEBCBS 1. A r Ъ u с о г В.A. «t al. - SOT.Journ.Hucl.Phy».,1975,?1#13?t A r b tt s о т B.A. at al. - Soy.Journ.Bucl.Phye.,1975,22,173. 2. Chen M.S. «t al. - Жис1.Нцгво, 1977» B118, 345. 3. Aaratyan A.B. at al. Ж., Preprint ITBP, 1984, Я 99. leratyan А.1. et al. - Xbjra.Lett., 1985, 156B, 441. 4. A 1 Ь а г а В. «t al. - rhj-e.l»T.Lett., 1984, 53, 2465. libriebt •. at al. Pfaya.Latt., 1984, 146B, 25. 5. AmaeaoT T.T. at al. - *icl.Phya., 1981, B177» 365. А.Е.Асратян и др. Наблюдение каскадного радиационного распада псевдовокторного очарованного странного мезона. Работа постулата в ОЯГИ 16.04.86 Подписано к печати 16.04.86 TII7P8 :юр?лгт 60x90 I/I6 Офсета.печ. Усл.-печ.л.0,5. Уч.-изд.л.0,3. Тираж L'50 экз. Заказ 77 Индекс 3624 Цена 5 коп. Отпечатано в 1Ю2, 117259, Москва, БЛерецртщ<инс1сая,25 ИНДЕКС 3624 М..ПРЕПРИНТ ИТЭФ, 1086, N«77, с.1-8.
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  • Towards Resolution of the Enigmas of P-Wave Meson Spectroscopy
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by CERN Document Server LA-UR-97-717 Towards Resolution of the Enigmas of P -Wave Meson Spectroscopy L. Burakovsky∗ and T. Goldman† Theoretical Division, MS B285 Los Alamos National Laboratory Los Alamos, NM 87545, USA Abstract The mass spectrum of P -wave mesons is considered in a nonrelativistic constituent quark model. The results show the common mass degeneracy of the isovector and isodoublet states of the scalar and tensor meson nonets, and do not exclude the possibility of a similar degeneracy of the same states of the axial-vector and pseudovector nonets. Current experimental hadronic and τ- decay data suggest, however, a different scenario leading to the a1 meson mass o ' 1190 MeV and the K1A-K1B mixing angle ' (37 ± 3) . Possible ss¯ states of the four nonets are also discussed. Key words: quark model, potential model, P -wave mesons PACS: 12.39.Jh, 12.39.Pn, 12.40.Yx, 14.40.Cs 1 Introduction The existence of a gluon self-coupling in QCD suggests that, in addition to the conven- tional qq¯ states, there may be non-qq¯ mesons: bound states including gluons (gluonia and glueballs, and qqg¯ hybrids) and multiquark states [1]. Since the theoretical guid- ance on the properties of unusual states is often contradictory, models that agree in ∗E-mail: [email protected] †E-mail: [email protected] 1 the qq¯ sector differ in their predictions about new states. Among the naively expected signatures for gluonium are i) no place in qq¯ nonet, ii) flavor-singlet coupling, iii) enhanced production in gluon-rich channels such as J/Ψ(1S) decay, iv) reduced γγ coupling, v) exotic quantum numbers not allowed for qq¯ (in some cases).
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  • Nuclear Interaction from Effective Field Theory
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