Parton energy loss and momentum broadening at NLO in high temperature QCD plasmas

Abstract

We present an overview of a perturbative-kinetic approach to jet propagation, energy loss, and momentum broadening in a high temperature quark-gluon plasma. The leading-order kinetic equations describe the interactions between energetic jet-particles and a non-abelian plasma, consisting of on-shell thermal excitations and soft gluonic fields. These interactions include 2 ↔ 2 scatterings, collinear bremsstrahlung, and drag and momentum diffusion. We show how the contribution from the soft gluonic fields can be factorized into a set of Wilson line correlators on the light cone. We review recent field-theoretical developments, rooted in the causal properties of these correlators, which simplify the calculation of the appropriate Wilson lines in thermal field theory. With these simplifications lattice measurements of transverse momentum broadening have become possible, and the kinetic equations describing parton transport have been extended to next-to-leading order in the coupling g.

Basics of Thermal Field Theory

“…Referencing is sparse; on more advanced topics, as well as on historically accurate references, the reader is advised to consult the textbooks and review articles in Refs. [1][2][3][4][5][6][7][8][9][10][11][12].…”

Angular structure of jet quenching within a hybrid strong/weak coupling model

“…(See refs. [70][71][72][73][74][75] for reviews.) Based on these approaches, Monte Carlo tools for analyzing jet observables are being developed [76][77][78][79][80][81][82][83] and many phenomenological studies of jets in medium have been confronted with LHC measurements of a variety of jet observables , including intrajet observables like those that we shall focus on [85,89,99,101,104,[106][107][108][109].…”

Thermalization of mini-jets in a quark–gluon plasma

“…The latter is a priori suitable for a probe particle, or a dilute system of such particles, which can be distinguished from the thermal bath (like a heavy quark [45,46]), but can also be applied to the gluons from the jet with relatively large momenta p z ω T [47]. Indeed, the occupation numbers for the gluons generated via multiple branching remain very small down to ω = T , as we shall see (cf.…”

“…So long as the gluon under study has a relatively large energy ω T , it can be unambiguously distinguished from the thermal gluons, so it is possible to describe its dynamics by using the same methods as for other energetic probes, like a relativistic heavy quark (see e.g. [44][45][46][47]). In this subsection we shall use a Langevin description because of its formal simplicity.…”