Parton showers as sources of energy-momentum deposition in the QGP and their implication for shockwave formation at RHIC and at the LHC

TL;DR

This paper derives the energy-momentum distribution from partons and their gluons in a quark-gluon plasma, accounting for quantum interference effects, and explores how this influences shockwave formation in heavy ion collisions.

Contribution

It introduces a new calculation of energy-momentum transfer including quantum interference effects and couples it to hydrodynamics to study medium response.

Findings

Quantum interference modifies energy absorption rates.

Large-angle gluon emission affects shockwave formation.

Well-defined Mach cones are unlikely due to multiple energy sources.

Abstract

We derive the distribution of energy and momentum transmitted from a primary fast parton and its medium-induced bremsstrahlung gluons to a thermalized quark-gluon plasma. Our calculation takes into account the important and thus far neglected effects of quantum interference between the resulting color currents. We use our result to obtain the rate at which energy is absorbed by the medium as a function of time and find that the rate is modified by the quantum interference between the primary parton and secondary gluons. This Landau-Pomeranchuk-Migdal type interference persists for time scales relevant to heavy ion phenomenology. We further couple the newly derived source of energy and momentum deposition to linearized hydrodynamics to obtain the bulk medium response to realistic parton propagation and splitting in the quark-gluon plasma. We find that because of the characteristic large angle in-medium gluon emission and the multiple sources of energy deposition in a parton shower, formation of well defined Mach cones by energetic jets in heavy ion reactions is not likely.