GTMDs and the factorization of exclusive double Drell-Yan

TL;DR

This paper establishes the first rigorous factorization framework for the exclusive double Drell-Yan process using Soft Collinear Effective Theory, linking it to GTMDs, hard factors, and light-cone wave functions.

Contribution

It derives the first factorization formula for the exclusive double Drell-Yan process, connecting it to GTMDs and enabling resummation of logarithms in QCD.

Findings

Factorization of the differential cross section is achieved.

The hard factor can be derived from single inclusive Drell-Yan production.

Evolution equations for GTMDs and LCWFs are discussed.

Abstract

Different exclusive processes have been proposed to access the generalized transverse momentum dependent distributions (GTMDs) with no proof of factorization, which allows to rigorously define the GTMDs. Using Soft Collinear Effective Theory we derive for the first time the factorization of the differential cross section for the exclusive double Drell-Yan process for the exclusive double Drell-Yan process pion N to N' gamma* gamma* to N' (l^+l^-)(l^+l^-), for small transverse momenta of the photons in terms of a perturbatively calculable hard factor, GTMDs and light-cone wave functions (LCWFs). We find that the hard factor of the process can be obtained from single inclusive Drell-Yan production so that one can resum logarithms at high orders in QCD. We also discuss the evolution of the GTMDs and the LCWFs.