The η ^′ N interaction from a chiral effective model and η ^′-N bound state

Abstract

The η ^′ mass reduction in the nuclear medium is expected owing to the degeneracy of the pseudoscalar-singlet and octet mesons in the restoration of the spontaneous chiral symmetry breaking. In this study, we investigate the η ^′ N 2body interaction, which is the fundamental interaction of the in-medium η ^′ properties, using the linear sigma model as a chiral effective model. The η ^′ N interaction in the linear sigma model comes from the scalar meson exchange with U _A (1) symmetry effect and is found to be fairly strong attraction. The transition amplitude of η ^′ N to the η N channel is relatively small compared to that of elastic channel. From the analysis of the η ^′ N 2body system, we find a η ^′ N bound state with the binding energy 12.3-3.3iMeV. We expect that this strongly attractive two body interaction leads to a deep and attractive optical potential.