Eta-mesic nuclei

In this contribution we report on theoretical studies of η nuclear quasi-bound states in few- and many-body systems performed recently by the Jerusalem-Prague Collaboration [1, 2, 3, 4, 5]. Underlying energy-dependent ηN interactions are derived from coupled-channel models that incorporate the N^∗(1535) resonance. The role of self-consistent treatment of the strong energy dependence of subthreshold ηN amplitudes is discussed. Quite large downward energy shift together with rapid decrease of the ηN amplitudes below threshold result in relatively small binding energies and widths of the calculated η nuclear bound states. We argue that the subthreshold behavior of ηN scattering amplitudes is crucial to conclude whether η nuclear states exist, in which nuclei the η meson could be bound and if the corresponding widths are small enough to allow detection of these η nuclear states in experiment.