Electrical conductivity of the quark-gluon plasma from the low energy limit of photon and dilepton spectra

TL;DR

This paper uses fluid dynamics and experimental photon and dilepton spectra to estimate the electrical conductivity of the quark-gluon plasma, providing a method to constrain this property through high-energy nuclear collision data.

Contribution

It introduces a novel approach combining fluid dynamic simulations with spectral density analysis to extract the electrical conductivity of the quark-gluon plasma from experimental data.

Findings

Photon and dilepton yields depend on the plasma's electrical conductivity.

Simulations show how varying conductivity affects observable spectra.

Results suggest experimental data can constrain the plasma's electrical properties.

Abstract

Fluid dynamic considerations are used to determine the electric current spectral density in the regime of small energies and momenta. The spectral density in this regime is parameterized by the electric conductivity, the charge susceptibility, and the relaxation time for the electric current, which is needed for relativistic causality. Experimentally, the spectral function can be accessed through the production rates of photons and dileptons in the expanding quark-gluon plasma. We use fluid dynamic simulations of high energy nuclear collisions, together with the transport limit of the spectral density, to obtain photon and dielectron spectra for different values of the conductivity and relaxation times. The yields of photon and dileptons produced in the plasma are compared to the background from decays of short-lived hadrons. We discuss how experiments can constrain the electrical conductivity and associated relaxation time of the quark-gluon plasma.