Quantum partonic transport in QCD matter

TL;DR

This paper investigates gradient corrections to the transport equation for energetic light partons in dense QCD matter, revealing quantum effects at second order in gradients and providing a way to incorporate inhomogeneities into jet quenching models.

Contribution

It introduces a second-order gradient expansion of the partonic Wigner function evolution, unveiling quantum corrections and a new transport mechanism for inhomogeneous QCD media.

Findings

Quantum corrections at second order in gradients modify transport equations.

Gradient corrections to the jet quenching parameter are computed for inhomogeneous matter.

A novel transport process suitable for Monte Carlo simulations is proposed.

Abstract

We study gradient corrections to the transport equation for energetic light partons in dense QCD environments. In the diffusion limit, the transport dynamics is solely controlled by small-angle elastic scatterings, leading to transverse momentum broadening with respect to the parton's initial direction. Such a parton propagation is usually considered in the limit of transversely homogeneous matter. The transport processes admit a classical description and the transverse spatial dependence of the medium properties emerges only through the jet quenching parameter. In this work, we show that a gradient expansion of the all-order evolution equation for the partonic Wigner function leads to an evolution equation in the Boltzmann-diffusion form only up to the leading order in transverse gradients. At the second order in gradients, the quantum corrections associated with non-local interactions give rise to a novel transport that can be implemented in Monte Carlo simulations. In addition, using our results, we compute the gradient corrections to the jet quenching parameter in inhomogeneous matter.