Initial and Final State Interaction Effects in Small-x Quark Distributions

TL;DR

This paper investigates initial and final state interactions affecting small-x quark distributions in high-energy processes, demonstrating universality in some cases and deriving relations between different scattering channels within the color glass condensate framework.

Contribution

It extends the understanding of quark distribution universality and relations in small-x saturation physics using scalar-QED and QCD color glass condensate models.

Findings

Quark distributions are universal between DIS and Drell-Yan processes.

The $qq' o qq'$ channel contribution is non-universal but related via convolution.

Relations are established in the large $N_c$ limit.

Abstract

We study the initial and final state interaction effects in the transverse momentum dependent parton distributions in the small-$x$ saturation region. In particular, we discuss the quark distributions in the semi-inclusive deep inelastic scattering, Drell-Yan lepton pair production and dijet-correlation processes in $pA$ collisions. We calculate the quark distributions in the scalar-QED model and then extend to the color glass condensate formalism in QCD. The quark distributions are found universal between the DIS and Drell-Yan processes. On the other hand, the quark distribution from the $qq'\to qq'$ channel contribution to the dijet-correlation process is not universal. However, we find that it can be related to the quark distribution in DIS process by a convolution with the normalized unintegrated gluon distribution in the color glass condensate formalism in the large $N_c$ limit.