Spatial imaging of proton via leading-twist non-skewed GPDs with basis light-front quantization

TL;DR

This paper explores the internal structure of the proton by analyzing leading-twist generalized parton distributions (GPDs) using basis light-front quantization, providing insights into the proton's transverse spatial and momentum distributions.

Contribution

It introduces a novel calculation of six leading-twist proton GPDs at zero skewness within a basis light-front quantization framework, comparing results with lattice QCD and other methods.

Findings

Mellin moments of GPDs match lattice QCD results

Provides two-dimensional transverse spatial distributions of the proton

Offers form factors and angular momentum contributions from partons

Abstract

The internal image of the proton is unveiled by examining the generalized parton distributions (GPDs) at zero skewness, within the basis light-front quantized environment. Several distributions emerge when a quark is sampled with different currents depending upon the helicity arrangements of the active quark and the proton target. We investigate six of the eight leading-twist proton GPDs of the valence quarks, the helicity conserving distributions $(H, E, \tilde{H})$ and the helicity non-conserving $(H_T,E_T,\tilde{H}_T)$ distributions at skewness set to zero ($\zeta=0$). We consider purely transverse momentum transfer and, hence, obtain results describe only the proton's two-dimensional structure in the transverse plane. We present the Mellin moments of these distribution functions, where the first moment produces a form factor and the second Mellin moments help extract the information on partonic contributions to the hadronic angular momentum. We compare our results for the Mellin moments with those from lattice QCD and other approaches where available. We also present the GPDs in transverse position space.