QCD phase diagram at finite isospin chemical potential and temperature in an IR-improved soft-wall AdS/QCD model * * H.L. is Supported by the National Natural Science Foundation of China (11405074). D.L. is Supported by the National Natural Science Foundation of China (11805084), the PhD Start-up Fund of Natural Science Foundation of Guangdong Province (2018030310457) and Guangdong Pearl River Talents Plan

Abstract

We study the phase transition between the pion condensed phase and normal phase, as well as chiral phase transition in a two flavor ( ) IR- improved soft-wall AdS/QCD model at finite isospin chemical potential and temperature T. By self-consistently solving the equations of motion, we obtain the phase diagram in the plane of and T. The pion condensation appears together with a massless Nambu-Goldstone boson , which is very likely to be a second-order phase transition with mean-field critical exponents in the small region. When , the critical isospin chemical potential approximates to vacuum pion mass . The pion condensed phase exists in an arched area, and the boundary of the chiral crossover intersects the pion condensed phase at a tri-critical point. Qualitatively, the results are in good agreement with previous studies on lattice simulations and model calculations.