Nonextensive effects on QCD chiral phase transition with a chiral chemical potential

Abstract：

In this study, we investigate the QCD chiral phase diagram in the presence of a chiral chemical potential $ \mu_{5} $ based on nonextensive statistical mechanics. A feature of this new statistic is a dimensionless nonextensivity parameter q, which summarizes all possible effects violating the assumptions of Boltzmann-Gibbs (BG) statistics (when $ q\rightarrow1 $ , it returns to the BG case). Within the nonextensive Polyakov-Nambu-Jona-Lasinio model, we find that as $ \mu_{5} $ increases, the critical end point (CEP) in the $ T-\mu $ plane continues to $ \mathrm{CEP}_{5} $ in the $ T-\mu_{5} $ plane, and nonextensive effects have a significant impact on the evolution from the CEP to $ \mathrm{CEP}_{5} $ . Generally, with an increase in q, both the CEP and $ \mathrm{CEP}_{5} $ move in the direction of a lower temperature Tand larger chemical potential μ( $ \mu_{5} $ ). In addition, we find that chiral charge density $ n_{5} $ generally increases with T, μ, $ \mu_{5} $ , and q. Our study may provide useful hints about lattice QCD and relativistic heavy-ion collision experiments.