Interaction of eta-meson with light nuclei

Abstract

A microscopic treatment of $\eta$--nucleus scattering is presented. When applying the underlying exact integral equations, the excitation of the target are neglected, and an input $\eta N$ amplitude is chosen which reproduces the $S_{11}(1535)$ resonance. It is shown that the $\eta$--nucleus scattering lengths are quite sensitive to the $\eta N$ parameters and the nuclear wave functions. For a special choice of the parameters an $\eta {^4\!H}e$ quasi--bound state occurs.