Title：Chiral Phase Transition Temperature in (2 + 1)-Flavor QCD

Speaker：Dr. Sheng-Tai Li (李胜泰)， Central China Normal University

Time: October 28, 2019 , 10:00AM

Venue：333 Lecture Hall, Physics Building

Abstract：The chiral phase transition temperature T_c^0 is a fundamental quantity of QCD. To determine this quantity, we have performed simulations of (2 + 1)-flavor QCD using the Highly Improved Staggered Quarks (HISQ) action on N_tau=6, 8, 12 lattices and aspect ratios N_sigma/N_tau ranging from 4 to 7. In our simulations, we fix the strange quark mass value to its physical value m_s^phy, and the values of two degenerate light quark masses m_l are varied from m_s^phy/160 to m_s^phy/20 which correspond to a Goldstone pion mass m_pi ranging from 55 MeV to 160 MeV in the continuum limit. By investigating the light quark mass dependence and volume dependence of various chiral observables, e.g. chiral susceptibilities and Binder cumulants, we didn't find any evidence for a first order phase transition in our current quark mass window. To extract the chiral phase transition temperature T_c^0 in the chiral & continuum limit, we proposed two novel estimators T^-_60% and T_delta. The uncertainty in the determination of T_c^0 is also discussed. We also discuss the nature of the chiral phase transition in the chiral limit.