TMD factorization for dijets + photon production from the dilute-dense CGC framework

TL;DR

This paper derives a TMD factorization formula for photon and dijet production in proton-nucleus collisions within the CGC framework, extending previous results to more complex processes.

Contribution

It demonstrates for the first time that TMD factorization holds in the correlation limit for $2\to3$ processes within the CGC formalism.

Findings

Derived a simplified cross section in the correlation limit

Identified sensitivity to unpolarized and linearly-polarized gluon TMDs

Extended TMD factorization validity beyond $2\to2$ processes

Abstract

We calculate the production of a photon and two jets at forward rapidity in proton-nucleus collisions, within the hybrid dilute-dense framework in the Color Glass Condensate (CGC) formalism. After obtaining the cross section for both the quark- and gluon-initiated channels, we consider the correlation limit, in which the vector sum of the transverse momenta of the three outgoing particles is small with respect to the individual transverse momenta. In this limit, the cross section simplifies considerably and can be written in a factorized form, sensitive to various unpolarized and linearly-polarized transverse-momentum-dependent gluon distribution functions (gluon TMDs). Thus, we demonstrate for the first time that the emergence of a TMD factorization formula in the correlation limit, from CGC expressions, holds beyond the previously-considered simpler $2\to2$ processes.