GTMDs and the factorization of exclusive double Drell-Yan

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 pi N -> N 'gamma*gamma* -> 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. (c) 2023 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

Automated summary

Using the Soft Collinear Effective Theory, we derive the factorization of the differential cross section for the exclusive double Drell-Yan process for small transverse momenta. The factorization allows for a rigorous definition of the generalized transverse momentum dependent distributions (GTMDs), and involves a perturbatively calculable hard factor, GTMDs, and light-cone wave functions (LCWFs). We find that the hard factor can be obtained from single inclusive Drell-Yan production, enabling the resummation of logarithms at high orders in QCD. We also discuss the evolution of the GTMDs and LCWFs.