Deep inelastic scattering off quark-gluon plasma and its photon emissivity

TL;DR

This paper explores how lattice QCD calculations of Euclidean correlators at imaginary momenta can provide insights into photon emission and parton distribution functions in quark-gluon plasma, differentiating weak and strong coupling regimes.

Contribution

It introduces a novel lattice QCD approach to study photon emissivity and deep inelastic scattering in quark-gluon plasma using Euclidean correlators at imaginary momenta.

Findings

First exploratory lattice calculation of Euclidean correlator at imaginary momentum.

Demonstrates how these correlators probe photon emission in quark-gluon plasma.

Shows potential to reveal parton distribution functions in the medium.

Abstract

The photon emissivity of quark-gluon plasma probes the interactions in the medium and differs qualitatively between a weakly coupled and a strongly coupled plasma in the soft-photon regime. The photon emissivity is given by the product of kinematic factors and a spectral function associated with the two-point correlator of the electromagnetic current at lightlike kinematics. A certain Euclidean correlator at imaginary spatial momentum can be calculated in lattice QCD and is given by an integral over the relevant spectral function at lightlike kinematics. I present a first exploratory lattice calculation of this correlator. Secondly, I show how Euclidean correlators at imaginary spatial momenta can also be used to probe the regime of deep inelastic scattering off quark-gluon plasma, which reveals its parton distribution function.