Nuclear bound state of eta'(958) and partial restoration of chiral symmetry in the eta' mass

TL;DR

This paper explores how partial restoration of chiral symmetry in nuclear matter can significantly reduce the eta' meson mass, potentially leading to narrow bound states in nuclei observable through hadronic reactions.

Contribution

It demonstrates the expected mass reduction of the eta' meson in nuclear medium due to chiral symmetry restoration, suggesting the formation of observable bound states.

Findings

Eta' mass decreases by about 100 MeV at nuclear saturation density.

Strong attraction in eta' nuclear systems without large absorption.

Potential for observing narrow eta' bound states in light nuclei.

Abstract

The in-medium mass of the $\eta^{\prime}$ meson is discussed in a context of partial restoration of chiral symmetry in nuclear medium. The $\eta^{\prime}$ mass is expected to be reduced by order of 100 MeV at the saturation density. The reduction is a consequence of the suppression of the anomaly effect on the $\eta^{\prime}$ mass induced by partial restoration of chiral symmetry. This strong attraction in $\eta^{\prime}$ nuclear systems does not accompany large absorption of $\eta^{\prime}$ into nuclear matter. This leads to the possibility of so narrow bound states of the $\eta^{\prime}$ meson in nuclei to be seen in hadronic reactions with light nuclear targets.