Chiral symmetry and the string description of excited hadrons

Abstract

A large symmetry group is perhaps experimentally observed in excited hadrons which includes the chiral group U(2)_L x U(2)_R as a subgroup. To possess this large symmetry a dynamical model for excited hadrons, presumably a string model, should explain formation of chiral multiplets and, at the same time, predict coinciding slopes of the angular and radial Regge trajectories. This is possible only if both the dynamics of the string and the chirality of the quarks at the ends of the string are considered together. We construct a model-independent unitary transformation from the relativistic chiral basis to the ^{2S+1}L_J basis, commonly used in hadronic phenomenology as well as in the string models, and demonstrate that a hadron belonging to the given chiral representation is a fixed superposition of the basis vectors with different L's and S's. Thus the description of highly excited hadron in terms of a fixed L is not compatible with chiral symmetry and has to be disregarded in favour of the description in terms of the total hadron spin J. Therefore, dynamics of the string must deliver the principal quantum number ~n+J, in order chiral multiplets with different spins to become degenerate, as required by the large symmetry group.

RevTeX, 5 pages, a few footnotes have been added, to appear in PRD

References in corpus (6)

• Linear Confinement and AdS/QCD
• Restoration of chiral and $U(1{)}_A$ symmetries in excited hadrons
• Light meson spectrum and classical symmetries of QCD
• Chiral symmetry patterns of excited mesons with the Coulomb-like linear confinement
• Effective restoration of chiral symmetry in excited mesons
• The large degeneracy of excited hadrons and quark models

Cited by in corpus (13)

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• ABC effect as a signal of chiral symmetry restoration in hadronic collisions
• SU(4) symmetry of the dynamical QCD string and genesis of hadron spectra
• Derivative sources in lattice spectroscopy of excited light-quark mesons
• High-spin mesons below 3 GeV
• Dibaryon resonances and short-range $NN$ interaction
• Angular momentum content of the rho-meson in lattice QCD
• Chiral symmetry, the angular content of the vector current in QED and QCD, and the holographic description of hadrons
• Effective chiral restoration in the rho'-meson in lattice QCD
• Chiral symmetry and the properties of hadrons in the Generalised Nambu-Jona-Lasinio model
• Isospin symmetry breaking in double-pion production in the region of $d^{\ast }(2380)$ and the scalar $\sigma$ meson
• QCD symmetries in excited hadrons
• Angular momentum decomposition of chiral multiplets in front form