Two-Flavor Chiral Phase Transition in Lattice QCD with the Kogut-Susskind Quark Action

A summary is presented of a scaling study of the finite-temperature chiral phase transition of two-flavor QCD with the Kogut-Susskind quark action based on simulations on $L^3\times 4$ ($L$=8, 12 and 16) lattices at the quark mass of $m_q=0.075,0.0375,0.02$ and 0.01. We find a phase transition to be absent for $m_q\ge 0.02$, and also quite likely at $m_q=0.01$. The quark mass dependence of susceptibilities is consistent with a second-order transition at $m_q=0$. The exponents, however, deviate from the O(2) and O(4) values theoretically expected.