The Chiral Phase Transition of Hot QCD from the Exact Renormalization Group

Abstract

The chiral phase transition of the finite temperature QCD is discussed in the ladder approximated Exact (Wilson's) Renormalization Group (ERG). The gluon thermal mass is incorporated by the Hard Thermal Loop (HTL) approximation. We calculated a critical temperature $T_c$, a critical exponent $\nu$, and order parameters such as chiral condensate $<\bar{\psi}\psi>$ and pion decay constants with this approximation. The dependences of the pion decay constants on an unphysical parameter are fairly improved by including contributions from momentum dependent vertices. The critical temperature was found as: $T_c\approx 124$ MeV for 3-flavors. It was shown that the critical temperature considerably depends on the approximation scheme for the gluon thermal mass term. We also calculated the temperature dependence of the chiral condensate, $\pi$ decay constants, and the pion velocity.