Inclusive Photoproduction of $\eta$ Mesons on Nuclei and the in-medium properties of the S$_{11}$ Resonance

Abstract

A relativistic non-local model for the inclusive photoproduction of $\eta$ mesons from complex nuclei is introduced. The model is based on the dominance of the S$_{11}$(1535) resonance. We compare the results of our calculations with the available data on inclusive cross sections for the nuclei C, Al and Cu. Assuming the resonance propagates freely in the nuclear medium, we find that the calculated angular distribution and energy dependence of the cross sections reproduce the data in a reasonable fashion. The present non-local model allows the inclusion of density dependent mass and width in the calculations. Including these in the calculations reveals that the presently available data do not show clear preference for the inclusion of such modifications of the properties of the S$_{11}$(1535) in the nuclear medium.