Study of the potential transverse momentum and potential angular momentum within the scalar diquark model

TL;DR

This paper uses a scalar diquark model to investigate potential transverse momentum and angular momentum, linking these to initial/final state interactions and re-scattering effects in high energy scattering.

Contribution

It introduces a simplified scalar diquark model to estimate potential angular momentum related to re-scattering phenomena in high energy processes.

Findings

Potential angular momentum is non-zero, consistent with lattice results.

Re-scattering effects are key to understanding potential angular momentum.

The model provides a way to estimate potential angular momentum from quark transverse momentum.

Abstract

We make use of a simple scalar diquark model to study the potential transverse momentum and potential angular momentum, defined as the difference between the Jaffe-Manohar and Ji notions of transverse momentum and orbital angular momentum, respectively. A non-vanishing potential angular momentum has been previously found in lattice calculations and is believed to appear due to the effects of initial/final state interactions between the spectator system and the struck quark in high energy scattering processes. Such re-scattering phenomena are similar in nature to those who are responsible for generating the Sivers shift. This motivates us to search for an estimate of the potential angular momentum in terms of the expectation value of the transverse momentum of the struck quark.