Twist-3 transverse momentum dependent gluon distributions in a spectator model

TL;DR

This paper models twist-3 gluon transverse momentum dependent distributions in a nucleon using a spectator framework, analyzing their properties and verifying related equations of motion.

Contribution

It introduces a spectator model approach to compute twist-3 gluon TMDs and tests the validity of their equation of motion relations.

Findings

Equation of motion relations hold fairly well in the model.

The model distinguishes T-even and T-odd components of distributions.

Numerical analysis supports the spectator model's applicability.

Abstract

We study the twist-3 transverse momentum dependent distributions of gluons in a nucleon within a spectator model framework. In this model, the nucleon is described as emitting a virtual (time-like) gluon and an on-shell spectator particle, with the spectator mass treated continuously via a spectral function. The twist-3 gluon-gluon correlators, $\Phi^{+i;+-}$ and $\Phi^{ij;l+}$, are parameterized by a set of complex functions, whose real and imaginary parts correspond to T-even and T-odd components, respectively. We numerically check the equation of motion relation for these distributions and find that relation holds fairly well in the spectator model.