Scaling of pseudocritical couplings in two-flavor QCD

We study the scaling behavior of the pseudocritical couplings for the chiral phase transition in two-flavor QCD. We show that all existing results from lattice simulations on lattices with the temporal extent $N_{\tau }=4,6, \mathrm{and} 8$ can be mapped onto a universal scaling curve. The relevant combination of critical exponents, $\beta \delta$, is consistent with the scaling behavior expected for a second-order phase transition with O(4) exponents. At present, the scaling according to the O(2) symmetry group can, however, not be ruled out.