Dynamics of glueball and production in the central region of pp collisions

Close, Frank; Kirk, A.; Schüler, G.

doi:10.1016/s0370-2693(00)00235-5

Cited by 34 publications

(23 citation statements)

References 17 publications

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“…The dk T (or ) dependence of central production has been studied intensively in nearly all WA102 publications; its implications are discussed in a series of papers by Close and collaborators [739,[742][743][744][745][746][747]. The study revealed two surprises.…”

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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“…They also provide copious data on γγ → light hadrons. Exploiting the dk T filter and φ dependences may separate qq states from those with gluonic admixtures or S-wave substructure (see later) [4]. Then there is the new opportunity for central production in proton-proton collisions at STAR and the proposal for this at HERA-g [3].…”

Section: Light Hadron Spectroscopy and Dynamics: Present And Futurementioning

confidence: 99%

The End of the Constituent Quark Model?

Close¹

2004

AIP Conference Proceedings

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In this conference summary talk at Hadron03, questions and challenges for Hadron physics of light flavours are outlined. Precision data and recent discoveries are at last exposing the limitations of the naive constituent quark model and also giving hints as to its extension into a more mature description of hadrons. These notes also pay special attention to the positive strangeness baryon $\Theta^+(1540)$ and include a pedagogic discussion of wavefunctions in the pentaquark picture, their relation with the Skyrme model and related issues of phenomenology.Comment: Conference Summary Talk Hadron 0

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“…Then, one could study, for instance, the distributions in the angle φ 12 between the transverse momenta p t,1 and p t,2 of the leading protons. For low-energy central-meson production these angular distributions have been extensively discussed in [7][8][9][10][11][12][13], [63][64][65], and from the tensor pomeron point of view in [33]. Angular distributions for glueball production have been discussed in [32].…”

Section: First Resultsmentioning

confidence: 99%

Central exclusive diffractive production of pp¯ pairs in proton-proton collisions at high energies

2018

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We consider the central exclusive production of the pp in the continuum and via resonances in protonproton collisions at high energies. We discuss the diffractive mechanism calculated within the tensorPomeron approach including Pomeron, Odderon, and Reggeon exchanges. The theoretical results are discussed in the context of existing WA102 and Intersecting Storage Rings experimental data, and predictions for planned or current experiments at the Relativistic Heavy Ion Collider and the LHC are presented. The distribution in y diff , the rapidity distance between the proton and antiproton, is particularly interesting. We find a dip at y diff ¼ 0 for the pp production, in contrast to the π þ π − and K þ K − production. We predict also the pp invariant-mass distribution to be less steep than for the pairs of pseudoscalar mesons. We argue that these specific differences for the pp production with respect to the pseudoscalar meson pair production can be attributed to the proper treatment of the spin of produced particles. We discuss asymmetries that are due to the interference of C ¼ þ1 and C ¼ −1 amplitudes of pp production. We have also calculated the cross section for the pp → ppΛΛ reaction. Here, the cross section is smaller, but the characteristic feature for dσ=dy diff is predicted to be similar to pp production. The presence of resonances in the pp channel may destroy the dip at y diff ¼ 0. This opens the possibility to study diffractively produced resonances. We discuss the observables suited for this purpose.

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Dynamics of glueball and production in the central region of pp collisions

Abstract: We explain the φ and t dependences of mesons with J P C = 0 ±+ , 1 ++ , 2 ±+ produced in the central region of pp collisions. For the 0 ++ and 2 ++ sector this reveals a systematic behaviour in the data that appears to distinguish between qq and non-qq or glueball candidates.

Cited by 34 publications

References 17 publications

Glueballs, hybrids, multiquarks

Glueballs, hybrids, multiquarks

The End of the Constituent Quark Model?

Central exclusive diffractive production of pp¯ pairs in proton-proton collisions at high energies

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