Heavy-quark free energy at finite temperature with 2+1 flavors of improved Wilson quarks in fixed scale approach

TL;DR

This study investigates the temperature dependence of heavy-quark free energy in QCD with 2+1 flavors using lattice simulations, revealing short-distance insensitivity and screening effects at long distances.

Contribution

It provides a detailed analysis of heavy-quark free energy at finite temperature with improved Wilson quarks using a fixed scale approach, enabling precise temperature dependence studies.

Findings

Short-distance free energy converges to zero-temperature potential.

Long-distance free energy approaches twice the single-quark free energy.

Debye screening mass aligns with perturbative and previous lattice results.

Abstract

The free energy between a static quark and an antiquark is studied by using the color-singlet Polyakov-line correlation at finite temperature. We perform simulations on $32^3 \times 12$, 10, 8, 6, 4 lattices in the high temperature phase with the RG-improved gluon action and 2+1 flavors of the clover-improved Wilson quark action. Since the simulations are based on the fixed scale approach that the temperature can be varied without changing the spatial volume and renormalization factor, it is possible to investigate temperature dependence of the heavy-quark free energy without any adjustment of the overall constant. We find that, the heavy-quark free energies at short distance converge to the heavy-quark potential evaluated from the Wilson-loop operator at zero temperature, in accordance with the expected insensitivity of short distance physics to the temperature. At long distance, the heavy-quark free energies approach to twice the single-quark free energies, implying that the interaction between heavy quarks is screened. The Debye screening mass obtained from the long range behavior of the heavy-quark free energy is compared with results of the thermal perturbation theory and those of $N_f=2$ and $N_f=0$ lattice simulations.