Nontrivial center dominance in high temperature QCD

Abstract

We investigate the properties of quarks and gluons above the chiral phase transition temperature [Formula: see text], using the renormalization group (RG) improved gauge action and the Wilson quark action with two degenerate quarks mainly on a [Formula: see text] lattice. In the one-loop perturbation theory, the thermal ensemble is dominated by the gauge configurations with effectively [Formula: see text] center twisted boundary conditions, making the thermal expectation value of the spatial Polyakov loop take a nontrivial [Formula: see text] center. This is in agreement with our lattice simulation of high temperature quantum chromodynamics (QCD). We further observe that the temporal propagator of massless quarks at extremely high temperature [Formula: see text] remarkably agrees with the temporal propagator of free quarks with the [Formula: see text] twisted boundary condition for [Formula: see text], but differs from that with the [Formula: see text] trivial boundary condition. As we increase the mass of quarks [Formula: see text], we find that the thermal ensemble continues to be dominated by the [Formula: see text] twisted gauge field configurations as long as [Formula: see text] and above that the [Formula: see text] trivial configurations come in. The transition is similar to what we found in the departure from the conformal region in the zero-temperature many-flavor conformal QCD on a finite lattice by increasing the mass of quarks.