ηphotoproduction on the proton in a chiral constituent quark approach via a one-gluon-exchange model

Abstract

A formalism based on a chiral quark model ($\ensuremath{\chi}\mathrm{QM}$) approach complemented with a one-gluon-exchange model, to take into account the breakdown of the $\mathrm{SU}(6)\ensuremath{\bigotimes}\mathrm{O}(3)$ symmetry, is presented. The configuration mixing of wave functions for nucleon and resonances are derived. With few adjustable parameters, differential cross-section and polarized-beam asymmetry for the $\ensuremath{\gamma}p\ensuremath{\rightarrow}\ensuremath{\eta}p$ process are calculated and successfully compared with the data in the center-of-mass energy range from threshold to 2 GeV. The known resonances ${S}_{11}(1535),{S}_{11}(1650),{P}_{13}(1720),{D}_{13}(1520)$, and ${F}_{15}(1680)$, as well as two new ${S}_{11}$ and ${D}_{15}$ resonances, are found to be dominant in the reaction mechanism. Moreover, connections among the scattering amplitudes of the $\ensuremath{\chi}\mathrm{QM}$ approach and the helicity amplitudes, as well as decay widths of resonances, are established. Possible contributions from the so-called missing resonances are investigated and found to be negligible.