Width of bound eta in nuclei

Abstract

Assuming the ηN interaction is dominated by the ${\mathit{N}}^{\mathrm{*}}$(1535) excitation we evaluate an η-nucleus optical potential that takes into account the free decay modes of the ${\mathit{N}}^{\mathrm{*}}$ plus its many-body decay modes up to one-particle-hole excitation. The potential is able to generate bound states in light and heavy nuclei but provides large widths for these states. The results are highly sensitive to the value of Re${\mathrm{\Sigma }}_{\mathit{N}}^{\mathrm{*}}$. In general, the widths are larger than the separation between the levels, although for Re${\mathrm{\Sigma }}_{\mathit{N}}^{\mathrm{*}}$ sufficiently repulsive a few narrow states can be found. In connection with a recent experiment our results suggest a potential for the ${\mathit{N}}^{\mathrm{*}}$ more attractive than for nucleons.