Scaling of Chiral Order Parameter in Two-Flavor QCD

The finite temperature transition of QCD with two degenerate light quarks is studied on the lattice with a renormalization group improved gauge action and the Wilson quark action. We have made simulations on an 8³×4 lattice near the chiral transition point. It is shown that the chiral condensate, which is the order parameter of chiral symmetry, satisfies remarkably a scaling relation with the exponents of the three-dimensional $O(4)$ Heisenberg model. This indicates that the chiral transition in two-flavor QCD is of second order in the continuum limit.