TEMPERATURE-DEPENDENCE OF THE CHIRAL CONDENSATE FROM AN INTERACTING PION GAS

By exploiting the fact that the chiral condensate is related to the derivative of the free-energy density with respect to the bare quark mass we calculate the temperature dependence of the condensate ratio [qBARq]tau/[qBARq]0 from an interacting pion gas. When using the Weinberg Lagrangian at the Hartree level we find a depression of the condensate with temperature. For T < 100 MeV the results are in good agreement with chiral perturbation theory in the three loop approximation. Near T(c), however, there are marked differences due to the non-perturbative nature of our approach.