Eta-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}-15 MeV, some discrete states of C, O and Ne eta bound states 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. 
C. Y. Song, X. H. Zhong, L. Li and P. Z. Ning