$U_A(1)$ symmetry restoration at high baryon density

Jianing Li, Jin Gui, Pengfei Zhuang

Published 2022-09-27Version 1

We study the relation between chiral and $U_A(1)$ symmetries in quark-meson and Nambu--Jona-Lasinio models. The topological susceptibility describing $U_A(1)$ breaking contains two components, the condensate controlled one and the meson fluctuation one, and the $U_A(1)$ restoration is governed by their competition. In hot medium the condensates are melted but the fluctuation is enhanced, the $U_A(1)$ symmetry can therefore not be restored by temperature effect alone. The baryon density, however, reduces both the condensates and fluctuation, the $U_A(1)$ symmetry can only be restored in dense or dense and hot mediums. The strange condensate plays a weak role in the susceptibility, the chiral and $U_A(1)$ symmetry restoration happen at almost the same critical point.