On electric fields in hot QCD: infrared regularization dependence

TL;DR

This paper investigates how background electric fields affect hot QCD plasmas, clarifying discrepancies in electric susceptibility calculations and exploring implications for heavy-ion collisions and laser experiments.

Contribution

It identifies the origin of differences in electric susceptibility results at finite temperature and volume, and constructs a susceptibility model in a hadron resonance gas.

Findings

Discrepancies in susceptibility arise from different formalisms at nonzero temperature.

Exact fermion propagator analysis clarifies the origin of disagreement.

Constructed susceptibility model for low-temperature hadron resonance gas.

Abstract

We study the impact of background electric fields on a hot plasma of charged particles -- a setting relevant for the early stages of heavy-ion collisions as well as laser pulse experiments. Historically, the electric susceptibility -- encoding the behavior of the hot medium for weak fields -- has been defined within two different formalisms, leading to two distinct results at nonzero temperature. With the help of an exact fermion propagator in a homogeneous electric background field at nonzero temperature and finite volume on the one hand, and an improved perturbative result on the other, we identify the origin of this disagreement. The equilibrium conditions for the system are discussed and the role of the thermodynamic ensemble used to describe the system is highlighted. Finally, we construct the electric susceptibility in a simplified hadron resonance gas model, relevant for the strongly interacting medium in the low-temperature regime.