A search for charmonium states produced in central pp interactions at 450 GeV/c

Barberis, D.; Binon, Freddy; Close, Frank; Danielsen, K.M.; Donskov, S.V.; Earl, B.C.; Evans, D.; French, B. R.; Hino, T.; Inaba, S.; Jachołkowski, A.; Jacobsen, T.; Khaustov, G.V.; Kinson, J.B.; Kirk, A.; Кондашов, А. А.; Lednev, A.A.; Lenti, V.; Minashvili, I.; Peigneux, Jean Pierre; Romanovsky, V.; Russakovich, N.; Semenov, A.; Shagin, P.; Shimizu, H.; Singovsky, A.V.; Sobol, A.; Stassinaki, M.; Stroot, Jean-Pierre; Takamatsu, K.; Tsuru, T.; Baillie, O. Villalobos; Votruba, M.F.; Yasu, Y.

doi:10.1016/s0370-2693(00)00703-6

Cited by 2 publications

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“…The reduction factor is nearly compatible with the predicted 1 for Pomeron-Pomeron fusion and incompatible with the prediction of 0.2 for fusion. 2 A large number of centrally produced final states X has been studied by the WA102 collaboration, like , , [301], and KK [307][308][309]311], [315], [316], and [312], 3 [304,320], + − , , and [302,310], 4 [299,313,317], KK [300], [318], [303], K * K * and [305], baryon-antibaryon [306] and charmonium states [319]. Earlier experiments investigated the same channels but had smaller statistics.…”

Section: Central Productionmentioning

confidence: 99%

Glueballs, hybrids, multiquarks

2007

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Glueballs, hybrids and multiquark states are predicted as bound states in models guided by quantum chromo dynamics (QCD), by QCD sum rules or QCD on a lattice. Estimates for the (scalar) glueball ground state are in the mass range from 1000 to 1800 MeV, followed by a tensor and a pseudoscalar glueball at higher mass. Experiments have reported evidence for an abundance of meson resonances with 0 −+ , 0 ++ and 2 ++ quantum numbers. In particular, the sector of scalar mesons is full of surprises starting from the elusive and mesons. The a 0 (980) and f 0 (980), discussed extensively in the literature, are reviewed with emphasis on their Janus-like appearance as KK molecules, tetraquark states or qq mesons. Most exciting is the possibility that the three mesons f 0 (1370), f 0 (1500), and f 0 (1710) might reflect the appearance of a scalar glueball in the world of quarkonia. However, the existence of f 0 (1370) is not beyond doubt and there is evidence that both f 0 (1500) and f 0 (1710) are flavour octet states, possibly in a tetraquark composition. We suggest a scheme in which the scalar glueball is dissolved into the wide background into which all scalar flavour-singlet mesons collapse.There is an abundance of meson resonances with the quantum numbers of the . Three states are reported below 1.5 GeV/c 2 whereas quark models expect only one, perhaps two. One of these states, (1440), was the prime glueball candidate for a long time. We show that (1440) is the first radial excitation of the meson.Hybrids may have exotic quantum numbers which are not accessible by qq mesons. There are several claims for J P C = 1 −+ exotics, some of them with properties as predicted from the flux tube model interpreting the quark-antiquark binding by a gluon string. The evidence for these states depends partly on the assumption that meson-meson interactions are dominated by s-channel resonances. Hybrids with non-exotic quantum numbers should appear as additional states. Light-quark mesons exhibit a spectrum of (squared) masses which are proportional to the sum of orbital angular momentum and radial quantum numbers. Two states do not fall under this classification. They are discussed as hybrid candidates.The concept of multiquark states has received revived interest due to new resonances in the spectrum of states with open and hidden charm. The new states are surprisingly narrow and their masses and their decay modes often do not agree with simple quark-model expectations.Lattice gauge theories have made strong claims that glueballs and hybrids should appear in the meson spectrum. However, the existence of a scalar glueball, at least with a reasonable width, is highly questionable. It is possible that hybrids will turn up in complex multibody final states even though so far, no convincing case has been made for them by experimental data. Lattice gauge theories fail to identify the nonet of scalar mesons. Thus, at the present status of approximations, lattice gauge theories seem not to provide a trustworthy guide into unknown territory ...

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Section: Central Productionmentioning

confidence: 99%

Glueballs, hybrids, multiquarks

2007

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“…Since it is impossible to determine the mass and quantum numbers of the produced particles from the initial state, the analysis is often rather complicated or even ambiguous. For the WA102 experiment, which used a 450 GeV/c proton beam onto a fixed target it turned out to be difficult to look for mesons in the charmonium region due to energy limitations [6].…”

Section: Hadron Spectroscopy With Previous Achievementsmentioning

confidence: 99%

Future prospects for hadron physics at P ¯ ANDA

Wiedner

2011

Progress in Particle and Nuclear Physics

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Abstract:The PANDA experiment at the new FAIR facility will be the major hadron physics experiment at the end of this decade. It has an ambitious far-reaching physics program that spans the most fascinating topics that are emerging in contemporary hadron physics. The universality of the antiproton annihilation process, with either protons or nuclei as targets, allows physicists to address questions like the structure of glueballs and hybrids; to clarify the nature of the X, Y and Z states; to investigate electromagnetic channels in order to measure form factors of the nucleon; and to provide theory with input with respect to nonperturbative aspects of QCD. The possibility to use different nuclear targets opens the window for charm physics with nuclei or for color transparency studies, as well as for an intensive hypernuclear physics program. Previous experimental experience has clearly demonstrated that the key to success lies in high levels of precision complemented with sophisticated analysis methods, only possible with high statistics in the data set. However, since this puts many critical demands on the detector, PANDA's design has incorporated cutting-edge detector technologies that in some cases have surpassed even the requirements for LHC experiments. Contents:

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A search for charmonium states produced in central pp interactions at 450 GeV/c

Abstract: A search for centrally produced charmonium states has been presented. There is no significant evidence for any charmonium production. An upper limit of 2 nb is found for the cross section of χ c production using the decay χ c (1P ) → J/ψγ.

Cited by 2 publications

References 9 publications

Glueballs, hybrids, multiquarks

Glueballs, hybrids, multiquarks

Future prospects for hadron physics at P ¯ ANDA

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