# Transverse momentum dependence in double parton scattering

## TL;DR

This review discusses the current understanding of transverse momentum dependence in double parton scattering, including theoretical frameworks, factorisation proofs, and future research directions in high-energy particle physics.

## Contribution

It provides a comprehensive overview of TMD in DPS, integrating different regions and comparing with single scattering, highlighting recent progress in factorisation proofs and correlations.

## Key findings

- Unified expression for DPS cross section incorporating TMD effects
- Comparison of TMD in DPS with single parton scattering
- Discussion on the status of factorisation proofs for DPS

## Abstract

In this review, we describe the status of transverse momentum dependence (TMD) in double parton scattering (DPS). The different regions of TMD DPS are discussed, and expressions given for the DPS cross section contributions that make use of as much perturbative information as possible. The regions are then combined with each other as well as with single parton scattering to obtain a complete expression for the cross section. Particular emphasis is put on the differences and similarities to transverse momentum dependence in single parton scattering. We further discuss the status of the factorisation proof for double colour singlet production in DPS, which is now on a similar footing to the proofs for TMD factorisation in single Drell-Yan, discuss parton correlations and give an outlook on possible research on DPS in the near future.