Analysis of recent eta photoproduction data

TL;DR

This paper analyzes recent eta-meson photoproduction data from different experiments, compares them with a Regge model, and discusses potential baryon resonance excitations around 2.1 and 2.4 GeV.

Contribution

It provides a comprehensive comparison of recent experimental data with a Regge model and discusses the consistency and possible resonance signals in eta photoproduction.

Findings

Good agreement among recent data except for CLAS 2009

Energy-dependent renormalization can reconcile CLAS data

Possible baryon resonances at 2.1 and 2.4 GeV

Abstract

Recent data on eta-meson photoproduction off a proton target in the energy range 2 < sqrt{s} < 3 GeV are analyzed with regard to their overall consistency. Results from the ELSA and CLAS measurements are compared with predictions of a Regge model whose reaction amplitude was fixed via a global fit to pre-2000 measurements of differential cross sections and polarization observables for gamma p -> eta p at higher energies. We find that all recent experimental results on differential cross sections for eta-meson photoproduction are in good agreement with each other, except for the CLAS data from 2009. However, the latter can be made consistent with the other data at the expense of introducing an energy-dependent renormalization factor. We point out that there indications in the data for a possible excitation of baryon resonances with masses around 2.1 and 2.4 GeV.