Effect of the final state interaction of $\eta' N$ on the $\eta'$   photoproduction off nucleon
  We investigate the $\eta'$ photoproduction off the nucleon with a particular interest in the effect of the final-state interaction (FSI) of the $\eta'$ meson and nucleon $(\eta'N)$ based on three-flavor linear sigma model. We find an enhancement in the cross section of the $\eta'$ photoproduction near the $\eta'N$-threshold energy owing to the $\eta'N$ FSI. With the $\eta'$ meson at forward angles, the energy dependence near the $\eta'N$ threshold is well reproduced with the $\eta'N$ FSI. The cross section at backward angles can also be a good probe to investigate the strength of the $\eta'N$ interaction. 
Shuntaro Sakai, Atsushi Hosaka, and Hideko Nagahiro
nucl-th hep-ph