Parton Distributions in the Impact Parameter Space

TL;DR

This paper explores how parton distributions in impact parameter space, affected by polarization and final state interactions, explain transverse single-spin asymmetries and relate to forces on quarks in polarized deep inelastic scattering.

Contribution

It introduces the impact parameter space approach to parton distributions and links transverse deformations to observable spin asymmetries and quark forces.

Findings

Transverse deformation causes significant asymmetries.

Final state interactions contribute to naive-T odd effects.

Deformation relates to the transverse force on quarks.

Abstract

Parton distributions in impact parameter space, which are obtained by Fourier transforming GPDs, exhibit a significant deviation from axial symmetry when the target and/or quark is 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 can also be related to the transverse force acting on the active quark in polarized DIS at higher twist.