Mesons and hybrids in a relativistic many body theory

Abstract

Using a field theoretical, QCD inspired Hamiltonian formulated in the Coulomb gauge, relativistic many-body calculations are reported which reproduce the semiquantitative features of the observed meson and lattice glueball spectrums. Dynamical chiral symmetry breaking is achieved utilizing a BCS vacuum ansatz, yielding gap equations and realistic quark (and gluon) constituent masses and condensates. The excited hadron states are obtained by diagonalizing the effective Hamiltonian in a truncated Fock space using both the TDA and RPA. The meson spectrum, for a variety of spin and parities, is reasonably well described. In general, the two approaches differ minimally, except for the TT and 77 where only the RPA yields correct properties and a Goldstone boson in the chiral limit. Our unified model also describes hybrids and a three-body TDA calculation predicts exotic and non-exotic hybrid states all above 2 GeV. Our results are consistent with lattice and flux tube hybrid masses, suggesting that the recently observed 1~+ exotics below 2 GeV have an alternative, perhaps four quark, structure.