η-nucleus bound states in nuclei

The binding energies ∊ η and widths Γ η 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 U η ≈ −72 MeV. Comparing our results with the previous results, we find that the ηN scattering length a η N is indeed important to the calculations. With increasing nuclear density the effective mass of the η meson decreases.