Glueballs, Hybrids, Baryons and Pentaquarks: Hadron05 summary on light-quark spectroscopy

Klempt, E.

doi:10.1063/1.2176572

Cited by 6 publications

(4 citation statements)

References 13 publications

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“…There are a few indications that this may occur, [230,231], but it cannot be at a significant rate. Based on the absence of real evidence for normal glueballs [232], the default value for the R-glueball fraction in PYTHIA is 10%, and can be changed. Clearly a scenario in which glueballs are predominantly formed in the hadronisation step will have a large impact on experimental searches which rely on the reconstruction of tracks.…”

Section: Hadronisationmentioning

confidence: 99%

Stable massive particles at colliders

et al. 2007

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We review the theoretical motivations and experimental status of searches for stable massive particles (SMPs) which could be sufficiently long-lived as to be directly detected at collider experiments. The discovery of such particles would address a number of important questions in modern physics including the origin and composition of dark matter in the universe and the unification of the fundamental forces. This review describes the techniques used in SMP-searches at collider experiments and the limits so far obtained on the production of SMPs which possess various colour, electric and magnetic charge quantum numbers. We also describe theoretical scenarios which predict SMPs along with the phenomenology needed to model their production at colliders and interactions with matter. In addition, the interplay between collider searches and open questions in cosmology such as dark matter composition is addressed.

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Section: Hadronisationmentioning

confidence: 99%

Stable massive particles at colliders

et al. 2007

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“…The interaction Hamiltonian acting on the colour and spin degrees of freedom, and generalising (1), is…”

Section: The Chromomagnetic Hamiltonian a General Considerationsmentioning

confidence: 99%

Chromomagnetism, flavour symmetry breaking and S-wave tetraquarks

et al. 2006

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The chromomagnetic interaction, with full account for flavour-symmetry breaking, is applied to S-wave configurations containing two quarks and two antiquarks. Phenomenological implications are discussed for light, charmed, charmed and strange, hidden-charm and double-charm mesons, and extended to their analogues with beauty. 12.39.Mk,12.40.Yx I. INTRODUCTIONThe question of the existence of multiquark hadrons beyond ordinary mesons and baryons has been addressed since the beginning of the quark model. It has been particularly discussed recently with the firm or tentative discovery of new hadron states in a variety of experiments. For a review of recent results, see, e.g., Refs. [1,2,3,4].Different mechanisms have been proposed to form stable or metastable multiquarks in the ground state. The most natural mechanism, especially for states close to a hadron-hadron threshold, is provided by nuclear forces, extrapolated from the nucleon-nucleon interaction, and acting between any pair of hadrons containing light quarks. This led several authors to predict the existence of DD * and D * D( + c.c.) molecules [5,6,7,8,9]. According to these authors (see, also, [10,11,12]), the latter configuration is perhaps seen in the X(3872) [13], though other interpretations have been proposed for this narrow meson resonance with hidden charm [14,15]. Stable or metastable multicharmed dibaryons are also predicted in this nuclear-physics type approach [16].Flavour independence is a key property of QCD, at least in the heavy-quark limit. Quarks are coupled to the gluon field through their colour, not their mass, and this induces a static interquark potential which is independent of the flavour content, in the same way as the same Coulomb interaction is kept acting on antiprotons, kaons, muons and electrons when exotic atoms and molecules are studied [17]. The mechanism by which the hydrogen molecule is more deeply bound than the positronium molecule remains valid, mutatis mutandis, in hadron physics with flavour independence and favours the binding of (QQqq) below the threshold of two heavy-flavoured mesons, when the quark-mass ratio Q/q increases [18,19,20,21,22,23,24,25].The best known mechanism for multiquark binding is based on spin-dependent forces. In the late 70's, Jaffe [26,27] proposed a (q 2q2 ) picture of some scalar mesons, as a solution to the puzzle of their low mass, decay and production properties, and abundance. He also discovered that the colour-spin operator entering the widelyaccepted models sometimes provides multiquark states with a coherent attraction which is larger than the sum of the attractive terms in the decay products, hence favouring the formation of bound states. An example is the so-called H dibaryon [28], with spin S = 0 and quark content (ssuudd), tentatively below any threshold * Electronic address: buccella@na.infn.it † Electronic address: hallstein.hogasen@fys.uio.no

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“…Not only there are mass inconsistencies among different experiments, evident tension between a small width and large production rates but also an exotic production mechanism would be needed to explain the lack of evidence at larger energies. But the most disturbing fact is the absence of the signal in some specific experiments where it is difficult to imagine a reason for not seeing it [10].…”

Section: Quantum Chromodynamicsmentioning

confidence: 99%