FATE OF THE CRITICAL LINE AND CHIRAL TRANSITION IN FINITE-TEMPERATURELATTICE QCD WITH THE WILSON QUARK ACTION

Finite-temperature phase structure of lattice QCD with the Wilson quar k action is analyzed. We show that the critical line at finite tempera tures, defined to be the line of vanishing pion screening mass, turns back toward strong coupling, forming a cusp on the (beta, K) plane, an d that the line of thermal transition runs past the tip of the cusp wi thout touching the critical line. Previous results are discussed in th e light of our findings.