An estimate for the thermal photon rate from lattice QCD

TL;DR

This paper estimates the photon production rate from quark-gluon plasma using lattice QCD, introducing a new correlation function and employing regularization techniques to improve accuracy in a specific momentum range.

Contribution

It proposes a new correlation function and applies both model-based and model-independent methods to estimate the photon rate from lattice QCD data.

Findings

Estimated photon rate in the momentum range {d7}T/2 to 2{d7}T

Improved control over systematic uncertainties

Application of Backus-Gilbert method for spectral function estimation

Abstract

We estimate the production rate of photons by the quark-gluon plasma in lattice QCD. We propose a new correlation function which provides better control over the systematic uncertainty in estimating the photon production rate at photon momenta in the range {\pi}T/2 to 2{\pi}T. The relevant Euclidean vector current correlation functions are computed with $N_{\mathrm f}$ = 2 Wilson clover fermions in the chirally-symmetric phase. In order to estimate the photon rate, an ill-posed problem for the vector-channel spectral function must be regularized. We use both a direct model for the spectral function and a model-independent estimate from the Backus-Gilbert method to give an estimate for the photon rate.