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

Abstract

A large approximate degeneracy of the excited hadron spectra, appears in the light meson spectra measured at LEAR, suggesting a novel principal quantum number n+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 2 n +j or 2 n +l spectrum, adding them may lead to the desired n+j pattern.