Heavy-Quark Free Energy, Debye Mass, and Spatial String Tension at Finite Temperature in Two Flavor Lattice QCD with Wilson Quark Action

TL;DR

This study investigates the behavior of heavy-quark free energies, Debye mass, and spatial string tension at finite temperature in two-flavor lattice QCD using Wilson quarks, providing insights into screening effects and comparing with perturbative theories.

Contribution

It presents the first detailed analysis of heavy-quark free energies and Debye mass in two-flavor Wilson quark lattice QCD at finite temperature, including comparisons with perturbative predictions and previous staggered quark results.

Findings

Heavy-quark free energies follow a screened Coulomb form at high temperature.

Debye mass's temperature dependence aligns with next-to-leading order thermal perturbation theory.

Spatial string tension agrees with effective theory predictions at high temperature.

Abstract

We study Polyakov loop correlations and spatial Wilson loop at finite Temperature in two-flavor QCD simulations with the RG-improved gluon action and the clover-improved Wilson quark action on a $ 16^3 \times 4$ lattice. From the line of constant physics at $m_{\rm PS}/m_{\rm V}=0.65$ and 0.80, we extract the heavy-quark free energies, the effective running coupling $g_{\rm eff}(T)$ and the Debye screening mass $m_D(T)$ for various color channels of heavy quark--quark and quark--anti-quark pairs above the critical temperature. The free energies are well approximated by the screened Coulomb form with the appropriate Casimir factors at high temperature. The magnitude and the temperature dependence of the Debye mass are compared to those of the next-to-leading order thermal perturbation theory and to a phenomenological formula in terms of $g_{\rm eff}(T)$. We make a comparison between our results with the Wilson quark action and the previous results with the staggered quark action. The spatial string tension is also studied in the high temperature phase and is compared to the next-to-next-leading order prediction in an effective theory with dimensional reduction.