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

TL;DR

This paper develops a chiral quark model with one-gluon exchange to analyze eta photoproduction on protons, successfully matching experimental data and identifying key resonances, while exploring the role of missing resonances.

Contribution

It introduces a combined chiral quark and one-gluon exchange framework to study eta photoproduction, including configuration mixing and resonance contributions, with minimal adjustable parameters.

Findings

Successful reproduction of differential cross-sections and beam asymmetries from threshold to 2 GeV.

Identification of dominant resonances such as $S_{11}(1535)$ and $D_{13}(1520)$ in the reaction.

Negligible contribution from missing resonances.

Abstract

A formalism based on a chiral quark model ($\chi$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 $\gamma p \to \eta p$ 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 $\chi$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.