Critical behavior at the chiral phase transition

It is generally expected that two-flavor QCD undergoes a high temperature chiral symmetry restoring phase transition at zero quark mass, with O(4) critical behavior[1]. Verifying this expectation is important for understanding the phenomenology of the transition and for facilitating an extrapolation of simulation data to physical quark masses. Lattice QCD at fixed Nt with staggered fermions is similarly expected to exhibit at least O(2) universality, with O(4) emerging in the continuum limit. For present purposes we do not distinguish O(2), O(4), or mean field critical behavior.