The Bayesian reconstruction of the in-medium heavy quark potential from lattice QCD and its stability

TL;DR

This paper non-perturbatively determines the complex in-medium heavy-quark potential from lattice QCD using a novel Bayesian spectral reconstruction, revealing a transition from confining to Debye-screened behavior and comparing with perturbative estimates.

Contribution

It introduces a new Bayesian method for spectral function extraction in lattice QCD to determine the heavy-quark potential at finite temperature, improving stability and reliability.

Findings

The real part of the potential transitions from linear confinement to Debye screening above deconfinement.

The potential's real part closely matches Coulomb gauge singlet free energies across temperatures.

The imaginary part is comparable to hard-thermal loop perturbation theory estimates.

Abstract

We report recent results of a non-perturbative determination of the static heavy-quark potential in quenched and dynamical lattice QCD at finite temperature. The real and imaginary part of this complex quantity are extracted from the spectral function of Wilson line correlators in Coulomb gauge. To obtain spectral information from Euclidean time numerical data, our study relies on a novel Bayesian prescription that differs from the Maximum Entropy Method. We perform simulations on quenched $32^3\times N_\tau$ $(\beta=7.0,\xi=3.5)$ lattices with $N_\tau=24,...,96$, which cover $839{\rm MeV} \geq T\geq 210 {\rm MeV}$. To investigate the potential in a quark-gluon plasma with light u,d and s quarks we utilize $N_f=2+1$ ASQTAD lattices with $m_l=m_s/20$ by the HotQCD collaboration, giving access to temperatures between $286 {\rm MeV} \geq T\geq 148{\rm MeV}$. The real part of the potential exhibits a clean transition from a linear, confining behavior in the hadronic phase to a Debye screened form above deconfinement. Interestingly its values lie close to the color singlet free energies in Coulomb gauge at all temperatures. We estimate the imaginary part on quenched lattices and find that it is of the same order of magnitude as in hard-thermal loop perturbation theory. From among all the systematic checks carried out in our study, we discuss explicitly the dependence of the result on the default model and the number of datapoints.