The electrical conductivity and soft photon emissivity of the QCD plasma

TL;DR

This paper calculates the electrical conductivity and soft photon emission rates of the quark-gluon plasma at high temperatures using lattice QCD simulations, revealing a low-energy spectral peak.

Contribution

It introduces a specialized method to analyze the spectral density near zero energy and provides the first continuum-limit estimates of conductivity and photon emissivity in this temperature range.

Findings

Detected a peak in the spectral density at small energies.

Estimated the electrical conductivity in the continuum limit.

Derived the soft photon emissivity from the spectral data.

Abstract

The electrical conductivity in the hot phase of the QCD plasma is extracted from a quenched lattice measurement of the Euclidean time vector correlator for 1.5 < T/T_c < 3. The spectral density in the vicinity of the origin is examined using a method specially adapted to this region, and a peak at small energies is seen. The continuum limit of the electrical conductivity, and the closely related soft photon emissivity of the QCD plasma, are then extracted from a fit to the Fourier transform of the temporal vector correlator.