Study of the η-nucleus interaction in the pd→ 3He η reaction near threshold

A detailed study of the effect of the η-nucleus final state interaction (FSI) in the pd→ ³He η reaction close to threshold is presented. The FSI is incorporated through a T-matrix for η ³He elastic scattering, constructed using few body equations. This T-matrix accounts for off-shell and binding effects in η-nucleus scattering. The energy dependence of the data on the pd→ ³He η reaction near threshold is reproduced only after including the FSI. The off-shell and binding effects in η ³He scattering are found to be important. Given the uncertainty in the knowledge of the elementary η-nucleon interaction, the sensitivity of the pd→ ³He η cross section to different prescriptions of the elementary t-matrix, t_{ηN→ ηN} is also discussed.