π⁰ and η meson exchange interactions in the coherent η meson production in the nucleus

The energy transfer spectra have been calculated for the coherent $\eta$ meson production in the proton nucleus reaction. The elementary reaction occurring in the nucleus is considered as $ pN \to pN^*(1535) $; $ N^*(1535) \to N\eta $. The $N^*(1535)$ excitation for the forward going proton and $\eta$ meson is occurred due to the $\pi^0$ and $\eta$ meson exchange interactions, other mesons do not contribute in this process. The cross sections are calculated for the $\pi^0$ and $\eta$ meson exchange interactions, and the effect of their interference on the cross section is also studied. The initial and final state interactions as well as the $N^*(1535)$ nucleus interaction are addressed by the optical potentials. The distorted wave functions for proton and $\eta$ meson are described by the eikonal form. The sensitivity of the cross section to the hadron nucleus potential is presented.