Screening of heavy quark free energies at finite temperature and non-zero baryon chemical potential

TL;DR

This study investigates how heavy quark free energies and screening masses in 2-flavour QCD depend on baryon chemical potential using a Taylor expansion approach, revealing that screening masses increase with mu_b and align with perturbative predictions above T_c.

Contribution

It introduces a method to analyze mu_b dependence in heavy quark free energies using a 6th order Taylor expansion, providing new insights into screening behavior at finite density.

Findings

Free energies decrease with increasing mu_b for small values.

Screening masses increase with mu_b and match perturbative theory for T > 2 T_c.

Expansion coefficients for screening masses differ by a factor of 2 above T_c.

Abstract

We analyze the dependence of heavy quark free energies on the baryon chemical potential (mu_b) in 2-flavour QCD using improved (p4) staggered fermions with a bare quark mass of m/T = 0.4. By performing a 6th order Taylor expansion in the chemical potential which circumvents the sign problem. The Taylor expansion coefficients of colour singlet and colour averaged free energies are calculated and from this the expansion coefficients for the corresponding screening masses are determined. We find that for small mu_b the free energies of a static quark anti-quark pair decrease in a medium with a net excess of quarks and that screening is well described by a screening mass which increases with increasing mu_b. The mu_b-dependent corrections to the screening masses are well described by perturbation theory for T > 2 T_c. In particular, we find for all temperatures above T_c that the expansion coefficients for singlet and colour averaged screening masses differ by a factor 2.