Numerical evidence for a first-order chiral phase transition in lattice QCD with two light flavors

Finite-temperature behavior of quantum chromodynamics with two light dynamical flavors is studied by Langevin simulation on a $8^3$×4 lattice with the Kogut-Susskind quark action. It is found that the chiral transition strengthens as the quark mass $m_q$ decreases towards zero, changing from a continuous crossover at $m_q$a=0.2 to a first-order transition at $m_q$a=0.1. The critical coupling at $m_q$=0 is estimated to be ${\beta }_c$=6/$g_c^2$=5.29–5.32, and the physical scale of $T_c$≃(0.19–0.24)$m_{\rho }$. .AE