QCD phase diagram at imaginary baryon and isospin chemical potentials

Abstract

We explore the phase diagram of two-flavor quantum chromodynamics (QCD) at imaginary values of baryon and isospin chemical potentials, μB and μiso, analyzing the thermodynamic potential of QCD analytically and that of the Polyakov-loop extended Nambu–Jona-Lasinio (PNJL) model numerically. QCD has no pion condensation at imaginary μB and μiso, and therefore has discrete symmetries that are not present at real μB and μiso. The PNJL model possesses all the discrete symmetries. It can reproduce qualitatively lattice QCD data presented very recently.