Effects of nucleon resonances on $\eta$ photoproduction off the neutron reexamined

TL;DR

This study examines how nucleon resonances influence eta photoproduction off the neutron, using an effective Lagrangian and Regge approach, and compares results with recent experimental data.

Contribution

It provides a detailed analysis of nucleon resonance effects, including the narrow N(1685) resonance, on eta photoproduction observables using a combined theoretical framework.

Findings

Total and differential cross sections agree qualitatively with experimental data.

Double polarization observable E matches recent measurements.

Predicted beam asymmetry offers guidance for future experiments.

Abstract

We investigate $\eta$ photoproduction off the neutron target, i.e., $\gamma n \to \eta n$, employing an effective Lagrangian method combining with a Regge approach. As a background, we consider nucleon exchange in the $s$-channel diagram and $\rho$- and $\omega$-meson Regge trajectories in the $t$ channel. The role of nucleon resonances given in the Review of Particle Data Group in the range of $W \approx 1500 - 2100$ MeV and the narrow nucleon resonance $N(1685,1/2^+)$ is extensively studied. The numerical results of the total and differential cross sections, double polarization observable $E$, and helicity-dependent cross sections $\sigma_{1/2}$, $\sigma_{3/2}$ are found to be in qualitative agreement with the recent A2 experimental data. The predictions of the beam asymmetry are also given.