Eta and Etaprime Photoproduction on the Nucleon with the Isobar Model EtaMAID2018

TL;DR

The paper updates the EtaMAID isobar model with new high-precision data for eta and etaprime photoproduction, incorporating a Regge-cut background, extensive resonance analysis, and exploring a potential narrow resonance near 1900 MeV.

Contribution

It introduces a comprehensive update to the EtaMAID model, including new data, a refined background description, and a novel approach to avoid double counting in the overlap region.

Findings

Updated partial wave analyses for eta and etaprime photoproduction.

Identification of a potential narrow resonance near 1900 MeV.

Comparison of four different partial wave analyses.

Abstract

The isobar model EtaMAID has been updated with new and high precision data for eta and etaprime photoproduction on protons and neutrons from MAMI, ELSA, GRAAL and CLAS. The background is described in a recently developed Regge-cut model, and for the resonance part the whole list of nucleon resonances has been investigated with 21 N* states contributing to eta photoproduction and 12 N* states contributing to etaprime photoproduction. A new approach is discussed to avoid double counting in the overlap region of Regge and resonances. A comparison is done among four newly updated partial waves analyses for observables and partial waves. Finally, the possibility of a narrow resonance near W=1900 MeV is discussed, that would be able to explain unexpected energy and angular dependence of observables in p(gamma,etaprime)p near etaprime threshold.