Quark Orbital Angular Momentum and Final State Interactions

TL;DR

This paper explores the relationship between different definitions of quark orbital angular momentum using Wigner distributions, linking them to observable effects in deep-inelastic scattering experiments.

Contribution

It clarifies the connection between Ji and Jaffe-Manohar definitions of quark orbital angular momentum and interprets their difference in terms of final state interactions.

Findings

The difference between the two definitions relates to the change in orbital angular momentum after leaving the target.

The mechanism is analogous to those causing transverse single-spin asymmetries in semi-inclusive DIS.

Provides a theoretical framework connecting orbital angular momentum definitions to experimental observables.

Abstract

Definitions of orbital angular momentum based on Wigner distributions are used to discuss the connection between the Ji definition of the quark orbital angular momentum and that of Jaffe and Manohar. The difference between these two definitions can be interpreted as the change in the quark orbital angular momentum as it leaves the target in a DIS experiment. The mechanism responsible for that change is similar to the mechanism that causes transverse single-spin asymmetries in semi-inclusive deep-inelastic scattering.