QCD phase diagram at finite baryon and isospin chemical potentials

The phase structure of two-flavor QCD is explored for thermal systems with finite baryon- and isospin-chemical potentials, μB and μiso, by using the Polyakov-loop extended Nambu-Jona-Lasinio (PNJL) model. The PNJL model with the scalar-type eight-quark interaction can reproduce lattice QCD data at not only μiso=μB=0, but also μiso>0 and μB=0. In the μiso-μB-T space, where T is temperature, the critical endpoint of the chiral phase transition in the μB-T plane at μiso=0 moves to the tricritical point of the pion-superfluidity phase transition in the μiso-T plane at μB=0 as μiso increases. The thermodynamics at small T is controlled by √(σ2+π2) defined by the chiral and pion condensates, σ and π.