Multiple Scattering, Parton Energy Loss and Modified Fragmentation Functions in Deeply Inelastic eA Scattering

TL;DR

Modified quark fragmentation functions in deeply inelastic eA collisions and their QCD evolution equations are derived for the first time in the framework of multiple parton scattering and the results in the next-leading-twist depend on both diagonal and off-diagonal twist-four parton distributions.

Abstract

Modified quark fragmentation functions in deeply inelastic $eA$ collisions and their QCD evolution equations are derived for the first time in the framework of multiple parton scattering. Induced radiation gives rise to additional terms in the evolution equations and thus softens the modified quark fragmentation functions. The results in the next-leading-twist depend on both diagonal and off-diagonal twist-four parton distributions and the combination of which clearly manifests the LPM interference pattern. The predicted modification depends quadratically on the nuclear size ($A^{2/3}$). Generalization to the case of hot QCD medium is also discussed.

Figures (2)

• Figure 1: Diagrams for rescattering with gluons (a) and quarks (b) without and with gluon radiation (c) in deeply inelastic $eA$ scattering. Possible cuts are shown by the dashed lines
• Figure 2: The predicted modification to the quark fragmentation functions for three different values of initial quark energy $q^-=Q^2/2p^+x_B$. $x_A=0.04$ corresponds to $A\approx 200$