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

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.

eta meson under partial restoration of chiral symmetry in nuclear medium

We shed light upon the eta mass in nuclear matter in the context of partial restoration of chiral symmetry, pointing out that the U_{A}(1) anomaly effects causes the eta-eta mass difference necessarily through the chiral symmetry breaking. As a consequence, it is expected that the eta mass is reduced by order of 100 MeV in nuclear matter where partial restoration of chiral symmetry takes place. The discussion given here is based on Ref. [1].