An estimate for the thermal photon rate from lattice QCD

¹ Institute for Theoretical Physics, Goethe University, 60438 Frankfurt am Main, Germany
² Dept. of Physics and Astronomy, York University, Toronto, Ontario, M3J 1P3, Canada
³ Helmholtz-Institut Mainz, Johannes Gutenberg-Universität, 55099 Mainz, Germany
⁴ PRISMA Cluster of Excellence and Institute of Nuclear Physics, Johannes Gutenberg-Universität, 55128 Mainz, Germany

^* Speaker, e-mail: harris@him.uni-mainz.de
^** Speaker, e-mail: amsteinb@uni-mainz.de

Published online: 26 March 2018

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 πT/2 to 2πT. The relevant Euclidean vector current correlation functions are computed with N_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 modelindependent estimate from the Backus-Gilbert method to give an estimate for the photon rate.