Formation of η'(958)-mesic nuclei and axial U_A(1) anomaly at finite density

Abstract

We discuss the possibility to produce the bound states of the $η'(958)$ meson in nuclei theoretically. We calculate the formation cross sections of the $η'$ bound states with the Green function method for ($γ$,p) reaction and discuss the experimental feasibility at photon facilities like SPring-8. We conclude that we can expect to observe resonance peaks in ($γ$,p) spectra for the formation of $η'$ bound states and we can deduce new information on $η'$ properties at finite density. These observations are believed to be essential to know the possible mass shift of $η'$ and deduce new information of the effective restoration of the chiral $U_A(1)$ anomaly in the nuclear medium.