Onset of $\eta$ nuclear binding

TL;DR

This paper reviews recent theoretical studies on the conditions required for eta meson binding in light nuclei, emphasizing the importance of the eta-nucleon scattering length for nuclear binding.

Contribution

It provides a self-consistent computational analysis of eta-nuclear systems, highlighting the minimum eta-nucleon scattering length needed for binding in helium isotopes.

Findings

Re$\,a_{\eta N}$ must be at least 1 fm for $\eta\,^3$He binding

Re$\,a_{\eta N}$ must be at least 0.7 fm for $\eta\,^4$He binding

Self-consistent calculations support the threshold for eta-nuclear binding

Abstract

Recent studies of $\eta$ nuclear quasibound states by the Jerusalem-Prague Collaboration are reviewed, focusing on stochastic variational method self consistent calculations of $\eta$ few-nucleon systems. These calculations suggest that a minimum value Re$\,a_{\eta N} \approx 1$ fm (0.7 fm) is needed to bind $\eta\,^3$He ($\eta\,^4$He).