Toward an effective chiral model of high-temperature QCD

In an effort to expose the mechanism for chiral-symmetry restoration in high-temperature QCD, we use numerical simulations of lattice QCD with staggered fermions to obtain information about possible effective chiral models. We propose the strategy of comparing expressions built from expectation values of low-order polynomials of "macroscopic" meson fields, such as a "Mexican-hat statistic'' (rr2 σ) / (rr 2) (σ) - 1, computed locally in terms of the quark fields in lattice QCD and in terms of the meson fields in the effective model. We find that, at least at our chosen couplings, QCD behaves like a nonlinear a model with little change in the local effective potential across the phase transition. This conclusion supports the hypothesis that chiral-symmetry restoration occurs through random fluctuations in a fixed-length order parameter. Included in this work is a thorough test of symmetry breaking and restoration as manifested in the nonlocal staggered chiral fields.