High-Energy QCD factorization from DIS to pA collisions

TL;DR

This paper discusses high-energy QCD factorization in deep inelastic scattering and proton-nucleus collisions, showing how it reduces to known forms and identifying the factorization components at one-loop level.

Contribution

It demonstrates the reduction of rapidity factorization to $k_{T}$-factorization in DIS and details the factorization structure in pA collisions using Wilson line formalism.

Findings

Factorization in DIS reduces to $k_{T}$-factorization with 2-gluon approximation.

Inclusive pA cross-section factorizes into PDFs, fragmentation functions, and dipole gluon distribution.

One-loop level analysis confirms the factorization structure.

Abstract

The high-energy QCD factorization for Deep Inelastic Scattering and for proton-nucleus collisions using Wilson line formalism and factorization in rapidity is discussed. We show that in DIS the factorization in rapidity reduces to the $k_{\rm T}$-factorization when the 2-gluon approximation is applied, provided that the composite Wilson line operator is used in the high-energy Operator Product Expansion. We then show that the inclusive forward cross-section in proton-nucleus collisions factorizes in parton distribution functions, fragmentation functions and dipole gluon distribution function at one-loop level.