  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].

Nuclear Theory;High Energy Physics - Phenomenology;Nuclear Experiment