# Exploring twist-2 GPDs through quasi-distributions in a diquark spectator model

## TL;DR

This paper investigates the behavior of quasi-GPDs in a diquark model, analyzing their approach to standard GPDs at high momenta, and explores their relation to quark angular momentum and higher-twist effects.

## Contribution

It extends the study of quasi-GPDs to all six leading-twist distributions within a diquark model, analyzing their properties and relations to standard GPDs and angular momentum.

## Key findings

- All quasi-GPDs reduce to standard GPDs at high hadron momenta.
- Numerical mismatch between quasi-GPDs and GPDs decreases with increasing momentum.
- Results provide insights into higher-twist effects and the relation to quark angular momentum.

## Abstract

Quasi parton distributions (quasi-PDFs) are currently under intense investigation. Quasi-PDFs are defined through spatial correlation functions and are thus accessible in lattice QCD. They gradually approach their corresponding standard (light-cone) PDFs as the hadron momentum increases. Recently, we investigated the concept of quasi-distributions in the case of generalized parton distributions (GPDs) by calculating the twist-2 vector GPDs in the scalar diquark spectator model. In the present work, we extend this study to the remaining six leading-twist GPDs. For large hadron momenta, all quasi-GPDs analytically reduce to the corresponding standard GPDs. We also study the numerical mismatch between quasi-GPDs and standard GPDs for finite hadron momenta. Furthermore, we present results for quasi-PDFs, and explore higher-twist effects associated with the parton momentum and the longitudinal momentum transfer to the target. We study the dependence of our results on the model parameters as well as the type of diquark. Finally, we discuss the lowest moments of quasi distributions, and elaborate on the relation between quasi-GPDs and the total angular momentum of quarks. The moment analysis suggests a preferred definition of several quasi-distributions.