symmetry restoration at high baryon density*

This is the authors' abstract. We don't add key points for this paper.

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