Towards a parameter-free analysis of the QCD chiral phase transition and its universal critical behavior

To quantify the universal properties of chiral phase transition in (2+1)-flavor QCD, we use an improved, renormalized order parameter for the chiral symmetry breaking. We construct ratios of this divergence-free order parameter from its values for different pairs of light quark masses. From this, we determine in a parameter-independent manner, the chiral phase transition temperature $T_c$ and the associated critical exponent $\delta$ of the universality class. We present first numerical results of these calculations on $N_\tau=8$ lattices, with staggered fermions.