QCD phase diagram at finite isospin and baryon chemical potentials with the self-consistent mean field approximation

Abstract

The self-consistent mean field approximation of two-flavor NJL model with introducing a free parameter α to reflect the competition between "direct" channel and the "exchange" channel, is employed to study QCD phase structure at finite isospin chemical potential µI , finite baryon chemical potential µB and finite temperature T , especially the location of the QCD critical point. It is found that, for fixed isospin chemical potentials the lower temperature of phase transition is obtained with α increasing in the T − µI plane, and the largest difference of the phase transition temperature with different α's appears at µI ∼ 1.5mπ. At µI = 0 the temperature of the QCD critical end point (CEP) decreases with α increasing, while the critical baryon chemical potential increases. At high isospin chemical potential (µI = 500 MeV), the temperature of the QCD tricritical point (TCP) increases with α increasing, and in the regions of low temperature the system will transit from pion superfluidity phase to the normal phase as µB increases. At low temperatures, the critical temperature of QCD phase transition with different α's rapidly increases with µI at the beginning, and then increases smoothly around µI > 300 MeV. In high baryon density region, the increase of the isospin chemical potential will raise the critical baryon chemical potential of phase transition.