Generalized Parton Distributions, Deeply Virtual Compton Scattering and TMDs

TL;DR

This paper explores how generalized parton distributions (GPDs) and their Fourier transforms reveal transverse deformations in parton distributions, explaining single-spin asymmetries and the transverse forces on quarks in polarized deep inelastic scattering.

Contribution

It links impact parameter space deformations of GPDs to observable spin asymmetries and higher-twist effects, providing a unified framework for understanding transverse spin phenomena.

Findings

Impact parameter space distributions show significant transverse deformation.

Deformation combined with final state interactions explains naive-T odd asymmetries.

Deformations relate to the transverse force on quarks in polarized DIS.

Abstract

Parton distributions in impact parameter space, which are obtained by Fourier transforming GPDs, exhibit a significant deviation from axial symmetry when target and/or quark are transversely polarized. In combination with the final state interactions, this transverse deformation provides a natural mechanism for naive-T odd transverse single-spin asymmetries in semi-inclusive DIS. The deformation of PDFs in impact parameter space can also be related to the transverse force acting on the active quark in polarized DIS at higher twist.