η-mesic nuclei in relativistic mean-field theory

With the eta-nucleon (eta N) interaction Lagrangian deduced from chiral perturbation theory, we study the possible eta-mesic nuclei in the framework of relativistic mean-field theory. The eta single-particle energies are sensitive to the eta N scattering length, and increase monotonically with the nucleon number A. If the scattering length is in the range of a(eta N) = 0.75-1.05 fm and the imaginary potential V-0 similar to 15 MeV, some discrete states of C-12(eta), O-16(eta) and Ne-20(eta) should be identified in experiments. However, when the scattering length a(eta N) < 0.5 fm, or the imaginary potential V-0 > 30 MeV, no discrete eta-meson bound states could be observed in experiments. Copyright (C) EPLA, 2008.