Parity doubling and highly excited mesons

Bugg, D.V.

doi:10.1016/j.physletb.2009.09.017

Cited by 2 publications

(2 citation statements)

References 29 publications

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“…Therefore one can hope that even a small contribution of the 4 −+ partial wave can be identified from such interference. The solution reported in [1] and investigated in [26] found a rather small 4 −+ partial wave which was described by the Breit-Wigner resonance with mass 2328±38 MeV and width 240±90 MeV. The contributions from the 4 ++ f 4 (2050) and 4 −+ η 4 (2328) states to the pp → 2π 0 η cross section integrated over all decay modes are shown in Fig.…”

Section: Fit Of the Datamentioning

confidence: 82%

Some indication for a missing chiral partnerη4around 2 GeV

Glozman

Sarantsev

2010

Phys. Rev. D

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The high-lying mesons in the light quark sector previously obtained from the partial wave analysis of the proton-antiproton annihilation in flight at 1.9 -2.4 GeV region at CERN reveal a very high degree of degeneracy. This degeneracy can be explained as due to an effective restoration of both SU (2)L × SU (2)R and U (1)A symmetries combined with a principal quantum number ∼ n + J. In this case there must be chiral partners for the highest spin states in the 2 and 2.3 GeV bands presently missing in the data. Here we reanalyze the Crystal Barrel data and show an indication for existence of the missing 4 −+ state around 2 GeV. This result calls for further experimental search of the missing states both in the proton-antiproton annihilation and in the production reactions.

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Section: Fit Of the Datamentioning

confidence: 82%

Some indication for a missing chiral partnerη4around 2 GeV

Glozman

Sarantsev

2010

Phys. Rev. D

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“…(15), with the quark degrees of freedom only, should provide a good approximation to the exact numerical solution of Llanes-Estrada and Cotantch [28] and of Glozman and Wagenbrunn [7]. Note added in proof -Very recently Bugg reanalysed Cristal Barrel data at LEAR [31] and his spectrum shows clearly the large degeneracy, where the angular excitations have the same scale as the radial-like excitations. However he found no evidence for parity doublets in the leading Regge Trajectory, but only in daughter trajectories.…”

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confidence: 97%

Gluon excitations and quark chiral symmetry in the meson spectrum: An einbein solution to the large degeneracy problem of light mesons

Bicudo¹

2010

Phys. Rev. D

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A large approximate degeneracy appears in the light meson spectrum measured at the CERN low energy antiproton ring, suggesting a novel principal quantum number n þ j in QCD spectra. We recently showed that the large degeneracy could not be understood with state-of-the-art confining and chiral invariant quark models, derived in a truncated Coulomb gauge. To search for a solution to this problem, here we add the gluon or string degrees of freedom. Although independently the quarks or the gluons would lead to a 2n þ j or 2n þ l spectrum, adding them together may lead to the desired n þ j pattern.To understand the large degeneracy of the light meson spectrum [1-5] observed by the Crystal Barrel Collaboration at the CERN low energy antiproton ring (LEAR), we include by the same token both bosonic and fermionic excitations. This is relevant for the observation of excited mesons in the new generation of experiments, say PANDA at the Facility for Antiproton and Ion Research, and in lattice QCD. We first describe the degeneracy, where the meson mass squared M 2 in the excited meson spectrum is led by the principal quantum number n þ j. Then we review the status of gluon string excitations with an M 2 possibly of the order of 2ð2n þ lÞ. Recently we have shown [5] that the quark degrees of freedom are not sufficient to understand the excited light meson spectrum, finding that the chiral invariant and confining quark model has an M 2 of the order of 2ð2n þ jÞ, with a prefactor which is correct for the angular l or j quantum numbers, but too large for the radial quantum number n. Importantly, both gluon and quark excitations have the same scale, with the string tension . Here we show that arriving at the desired n þ j pattern is possible if we include the gluon or string degrees of freedom in relativistic quark models with chiral symmetry breaking. For simplicity, in this first comprehensive study of a gluonic and chiral invariant high spectrum, we use einbeins to add the bosonic excitations to the fermionic excitations.

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Parity doubling and highly excited mesons

Cited by 2 publications

References 29 publications

Some indication for a missing chiral partnerη4around 2 GeV

Some indication for a missing chiral partnerη4around 2 GeV

Gluon excitations and quark chiral symmetry in the meson spectrum: An einbein solution to the large degeneracy problem of light mesons

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