Parton Energy Loss in Collinear Expansion

TL;DR

This paper clarifies that the N=1 rescattering contribution to gluon radiation vanishes in the collinear approximation, challenging previous higher-twist results that overlooked key terms.

Contribution

It identifies and corrects a mistake in prior higher-twist calculations by showing the importance of including all relevant terms in the collinear expansion.

Findings

N=1 rescattering contribution vanishes in collinear approximation

Previous higher-twist results are invalid due to neglected terms

Highlights importance of proper collinear expansion in gluon radiation studies

Abstract

We demonstrate that the N=1 rescattering contribution to the gluon radiation from a fast massless quark in eA DIS vanishes in the collinear approximation. It is shown that the nonzero N=1 gluon spectrum obtained in the higher-twist approach by Guo, Wang and Zhang is a consequence of unjustified neglecting some important terms in the collinear expansion.