Thermal QCD with external imaginary electric fields on the lattice

TL;DR

This paper investigates how QCD behaves at finite temperature when subjected to imaginary electric fields, focusing on electric susceptibility and addressing unique challenges in separating physical effects from gauge artifacts using lattice simulations.

Contribution

It provides the first lattice determination of electric susceptibility in finite-temperature QCD with imaginary electric fields, highlighting the need to distinguish physical effects from gauge-related artifacts.

Findings

Electric susceptibility computed at physical quark masses.

Identification of gauge artifacts related to chemical potential.

Methodology for separating genuine electric effects from spurious contributions.

Abstract

We study QCD at finite temperature in the presence of imaginary electric fields. In particular, we determine the electric susceptibility, the leading coefficient in the expansion of the QCD pressure in the imaginary field. Unlike for magnetic fields, at nonzero temperature this coefficient requires a non-trivial separation of genuine electric field-related effects and spurious effects related to the chemical potential, which becomes an unphysical gauge parameter in this setting. Our results are based on lattice simulations with stout improved dynamical staggered quarks at physical quark masses.