Jet-Medium Interactions at NLO in a Weakly-Coupled Quark-Gluon Plasma

TL;DR

This paper extends the effective kinetic approach to jet-medium interactions in a quark-gluon plasma to next-to-leading order, refining the description of energy loss mechanisms and introducing a new semi-collinear emission regime.

Contribution

It provides the first NLO calculation of jet-medium interaction coefficients and introduces a unified framework for collinear splittings, scatterings, and particle conversions.

Findings

NLO modifications to drag, diffusion, and splitting coefficients

Introduction of a semi-collinear emission regime at NLO

Evaluation method for Wilson line operators at NLO

Abstract

We present an extension to next-to-leading order in the strong coupling constant $g$ of the AMY effective kinetic approach to the energy loss of high momentum particles in the quark-gluon plasma. At leading order, the transport of jet-like particles is determined by elastic scattering with the thermal constituents, and by inelastic collinear splittings induced by the medium. We reorganize this description into collinear splittings, high-momentum-transfer scatterings, drag and diffusion, and particle conversions (momentum-preserving identity-changing processes). We show that this reorganized description remains valid to NLO in $g$, and compute the appropriate modifications of the drag, diffusion, particle conversion, and inelastic splitting coefficients. In addition, a new kinematic regime opens at NLO for wider-angle collinear bremsstrahlung. These semi-collinear emissions smoothly interpolate between the leading order high-momentum-transfer scatterings and collinear splittings. To organize the calculation, we introduce a set of Wilson line operators on the light-cone which determine the diffusion and identity changing coefficients, and we show how to evaluate these operators at NLO.