Study of $η$ photoproduction on the proton in a chiral constituent quark approach via one-gluon-exchange model

Abstract

A formalism based on a chiral quark model ($χ$QM) approach complemented with a one-gluon exchange model, to take into account the breakdown of the $SU(6)\otimes O(3)$ 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 $γp \to ηp$ process are calculated and successfully compared with the data in the centre-of-mass energy range from threshold up 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. Besides, connections among the scattering amplitudes of the $χ$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.

25 pages,3 figures