Parton Energy Loss in Collinear Expansion

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.

Comments: Contributed to 43rd Rencontres de Moriond on QCD and High-Energy Hadronic Interactions, La Thuile, Italy, 8-15 Mar 2008. 6 pages, 2 figures