Structure of the nucleon at leading and subleading twist in the covariant parton model

TL;DR

This paper extends the covariant parton model to systematically describe quark correlators, reproduces known results, and evaluates all T-even twist-3 TMDs for the first time, providing insights into their relations and numerical comparisons.

Contribution

It introduces a generalized covariant parton model that systematically evaluates all T-even twist-3 TMDs, including the unintegrated quark correlator.

Findings

Reproduces previous results for leading-twist TMDs

Evaluates all T-even twist-3 TMDs for the first time

Provides numerical results and compares with existing parametrizations

Abstract

The covariant parton model is generalized to describe quark correlators in a systematic way. Previous results are reproduced for the T-even leading-twist transverse momentum dependent parton distribution functions (TMDs), and for the first time all T-even twist-3 TMDs are evaluated in this model. We apply the approach to evaluate the fully unintegrated quark correlator which allows us to understand the model-specific relations between different TMDs. We verify the consistency of the approach, present numerical results and compare to available TMD parametrizations.