Collisional parton energy loss in a finite size QCD medium revisited: Off mass-shell effects

TL;DR

This paper investigates how off mass-shell effects influence collisional energy loss of particles in a finite QCD medium, revealing a reduction in energy loss that depends on the particles' in-medium lifetime scale.

Contribution

It introduces off mass-shell effects into the calculation of collisional energy loss in a finite medium, providing a more realistic model of particle propagation.

Findings

Off mass-shell effects reduce energy loss compared to on-shell particles.

The reduction is more significant when the in-medium lifetime scale is small.

Implications for parton recombination scenarios are discussed.

Abstract

We study the collisional energy loss mechanism for particles produced off mass-shell in a finite size QCD medium. The off mass-shell effects introduced are to consider particles produced in wave packets instead of plane waves and the length scale associated to an in-medium particles' life-time. We show that these effects reduce the energy loss as compared to the case when the particles are described as freely propagating from the source. The reduction of the energy loss is stronger as this scale becomes of the order or smaller than the medium size. We discuss possible consequences of the result on the description of the energy loss process in the parton recombination scenario.