η-nucleus bound states in nuclei

The binding energies η and widths Γη of η-mesic nuclei are calculated.We parameterize the η self-energy in the nuclear medium as a function of energy and density.We find that the single-particle energies are sensitive to the scattering length,and increase monotonically with the nucleus.The key point for the study of η-nucleus bound states is the η-nuclear optical potential.We study the s-wave interactions of η mesons in a nuclear medium and obtain the optical potential Uη ≈ -72 MeV.Comparing our results with the previous results,we find that the ηN scattering length aηN is indeed important to the calculations.With increasing nuclear density the effective mass of the η meson decreases.