$\eta^\prime$ meson under partial restoration of chiral symmetry in nuclear medium

TL;DR

This paper investigates how partial restoration of chiral symmetry in nuclear matter affects the eta' meson mass, predicting a significant reduction and potential bound state formation due to strong attraction.

Contribution

It demonstrates that the eta' meson mass decreases by about 100 MeV in nuclear matter and predicts the possible formation of eta'-N bound states.

Findings

Eta' mass reduces by approximately 100 MeV in nuclear medium.

Strong attraction in eta'-N system may lead to bound states.

Chiral symmetry restoration influences eta' meson properties.

Abstract

In-medium modification of the eta' mass is discussed in the context of partial restoration of chiral symmetry in nuclear medium. We emphasize that the U_A(1) anomaly effects causes the eta'-eta mass difference necessarily through the chiral symmetry breaking. As a consequence, the eta' mass is expected to be reduced by order of 100 MeV in nuclear matter where about 30% reduction of chiral symmetry takes place. The strong attraction relating to the eta' mass generation eventually implies that there should be also a strong attractive interaction in the scalar channel of the eta'-N two-body system. We find that the attraction can be strong enough to form a bound state.