UNIVERSAL SCALING PROPERTIES OF QCD CLOSE TO THE CHIRAL LIMIT

We present a lattice QCD based determination of the chiral phase transition temperature in QCD with two massless (up and down) and one strange quark having its physical mass. We propose and calculate two novel estimators for the chiral transition temperature for several values of the light-quark masses, corresponding to the Goldstone pion masses in the range of 58 MeV less than or similar to m(pi) less than or similar to 163 MeV. The chiral phase transition temperature is determined by extrapolating to vanishing pion mass using universal scaling relations. After thermodynamic, continuum and chiral extrapolations, we find the chiral phase transition temperature T-c(0) = 132(-6)(+3) MeV. We also show some preliminary calculations that use the conventional estimator for the pseudo-critical temperature and compare them with the new estimators for T-c(0). Furthermore, we show results for the ratio of the chiral order parameter and its susceptibility, and argue that this ratio can be used to differentiate between O(N) and Z(2) universality classes in a non-parametric manner.