QCD Corrections of All Structure Functions in Transverse Momentum Dependent Factorization for Drell-Yan Processes

TL;DR

This paper investigates one-loop QCD corrections to all structure functions in TMD factorization for Drell-Yan processes, revealing that their perturbative coefficients are identical at leading twist, and demonstrates the equivalence of different diagrammatic approaches.

Contribution

It introduces a systematic subtractive approach for calculating QCD corrections in TMD factorization and shows the equivalence of scattering of partons and hadrons in this context.

Findings

Perturbative coefficients of all structure functions are identical at leading twist.

The subtractive approach effectively isolates short-distance effects.

Scattering of multi-parton states reproduces results from the subtractive approach.

Abstract

We study the one-loop correction in Transverse-Momentum-Dependent(TMD) factorization for Drell-Yan processes at small transverse momentum of the lepton pair. We adopt the so-called subtractive approach, in which one can systematically construct contributions for subtracting long-distance effects represented by diagrams. The perturbative parts are obtained after the subtraction. We find that the perturbative coefficients of all structure functions in TMD factorization at leading twist are the same. The perturbative parts can also be studied with scattering of partons instead of hadrons. In this way, the factorization of many structure functions can only be examined by studying the scattering of multi-parton states, where there are many diagrams. These diagrams have no similarities to those treated in the subtractive approach. As an example, we use existing results of one structure function responsible for Single-Spin-Asymmetry, to show that these diagrams in the scattering of multi-parton states are equivalent to those treated in the subtractive approach after using Ward identity.