UA(1) symmetry restoration at high baryon density

We study the relation between chiral and U-A(1) symmetries in the quark-meson model. Although quarks and mesons are described in mean field approximation, the topological susceptibility characterizing U-A(1) the breaking comprises two components: one controlled by the condensate and the other by the meson fluctuation. The U-A(1) restoration is governed by the competition of these components. In a hot medium, the condensates melt. However, the fluctuation is enhanced. Therefore, the U-A(1) symmetry cannot be solely restored via the temperature effect. Nevertheless, the baryon density reduces the condensates and fluctuation, and thereby, the U-A(1) symmetry can only be restored in a dense or dense and hot medium. The strange condensate plays a weak role in the susceptibility, and the chiral and symmetry U-A(1) restorations occur almost at the same critical point.