Abstract

We derive the leading order matching of the quark generated polarized transverse momentum dependent (TMD) distributions onto the collinear functions at small values of the transverse distance. Starting from the very definition of the TMD operator and performing the light-cone operator product expansion up to twist-3 order, we evaluate each distribution directly in position space. We primarily consider the cases of Sivers, Boer-Mulders and worm-gear functions. The effects of the TMD process dependence on the matching are explicitly shown. We also discuss the moments of TMD distributions which can be relevant for lattice calculations.

Highlights

  • One of the modern challenges of QCD is represented by the study of the effects of polarization in differential cross sections for semi-inclusive deep inelastic scattering (SIDIS) and Drell-Yan/vector/scalar-boson production

  • The main aim of this paper is to uniformly evaluate the matching of quark TMD parton distribution functions (TMDPDFs) at the twist-3 level, using solely the definition of the transverse momentum dependent (TMD) distribution as it is provided by the TMD factorization theorem

  • In order to realize our computations we start observing that the operators that define TMD distributions have a peculiar structure, which distinguishes them from more traditional parton distribution functions (PDFs) and fragmentation functions (FFs), distributions amplitudes and others

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Summary

Introduction

One of the modern challenges of QCD is represented by the study of the effects of polarization in differential cross sections for semi-inclusive deep inelastic scattering (SIDIS) and Drell-Yan/vector/scalar-boson production. In order to realize our computations we start observing that the operators that define TMD distributions have a peculiar structure, which distinguishes them from more traditional parton distribution functions (PDFs) and fragmentation functions (FFs), distributions amplitudes and others They include half-infinite light-like Wilson lines, and they are geometrically non-compact. The direction of the Wilson lines depends on the underline process This direction is future pointing for production mechanisms (such as fragmentation in semi-inclusive deep-inelastic scattering (SIDIS)), and past pointing for collision mechanisms (such as Drell-Yan process). The collinear distributions are perfectly independent on the process, any process dependence of TMD operator must reveal itself within OPE We observe this effect and demonstrate that it appears in the contributions specific for the TMD operators.

Definition of TMD distributions
Light-cone expansion for TMD operator
Collinear distributions
Parameterization of quark–quark correlators
Parameterization of quark-gluon-quark correlators
Leading matching of TMD distributions
Vector operator
Axial operator
Tensor operator
Mellin moments of worm-gear functions
Conclusion
Function gT
Findings
Function hL
Full Text
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