Seminar on Hadronic Physics

The thermal photon rate at next-to-leading order

Jacopo Ghiglieri

McGill University

We present a calculation of the rate for photon production from a weakly-coupled quark-gluon plasma at next-to-leading order. We first give an overview of the leading-order (e²g²) result and show how it decomposes in a region dominated by 2<->2 processes (gq->γ q and qqbar->γ g) and in one dominated by collinear radiation processes. At NLO (e²g³) both regions receive order-g corrections from momenta of order gT. We show how Euclidean and sum rule techniques can be introduced and how this technological advancement renders the calculation simpler than expected. The resulting correction is O(15-20%) for α_s=0.3 and k/T<10.