Interference phenomena in the $J^P=1/2^-$-wave in $η$ photoproduction

Abstract

The recent precise experimental results for the photoproduction of $η$-mesons off the neutron measured with the Crystal Ball/TAPS calorimeter at the MAMI accelerator have been investigated in detail in the framework of the Bonn-Gatchina coupled channel model. The main result is that the narrow structure observed in the excitation function of $γn \rightarrow nη$ can be reproduced fully with a particular interference pattern in the $J^P=1/2^-$ partial wave. Introduction of the narrow resonance $N(1685)$ with the properties reported in earlier publications deteriorates the quality of the fit.

10 pages, 13 figures, accepted for publication in EPJA