eta-photoproduction in the resonance energy region

Abstract

The $\eta$ production in the nucleon resonance energy region is studied within the unitary coupled-channels effective Lagrangian approach of the Giessen model. We demonstrate that the second peak recently observed in the cross section of $\eta$ photoproduction on the neutron at $\sqrt{s}$=1.66 GeV can be explained in terms of coupled-channel effects due to $S_{11}(1650)$ and $P_{11}(1710)$ resonance excitations.