Eta-nuclear bound states revisited

TL;DR

This paper investigates eta-nuclear bound states by incorporating the energy-dependent eta-N scattering amplitude, revealing that a minimum Re a_{eta N} of about 0.9 fm is necessary for binding, with calculations across various nuclei.

Contribution

It introduces a self-consistent method that includes the energy dependence of eta-N interactions, providing new constraints on eta-nuclear binding conditions.

Findings

Re a_{eta N} must be approximately 0.9 fm for eta-4He binding

Binding energies and widths vary across different eta-N models

Evidence for eta-25Mg bound state is discussed

Abstract

The strong energy dependence of the s-wave eta-N scattering amplitude at and below threshold, as evident in coupled-channels K-matrix fits and chiral models that incorporate the S11 N*(1535) resonance, is included self-consistently in eta-nuclear bound-state calculations. This approach, applied recently in calculations of kaonic atoms and Kbar-nuclear bound states, is found to impose stronger constraints than ever on the onset of eta-nuclear binding, with a minimum value of Re a_{eta N} approximately 0.9 fm required to accommodate an eta-4He bound state. Binding energies and widths of eta-nuclear states are calculated within several underlying eta-N models for nuclei across the periodic table, including eta-25Mg for which some evidence was proposed in a recent COSY experiment.