Generalized parton distributions through universal moment parameterization: zero skewness case

TL;DR

This paper introduces a universal moment parameterization method for generalized parton distributions (GPDs), enabling simultaneous fits to phenomenological PDFs, lattice form factors, and direct lattice GPD calculations, enhancing understanding of proton structure.

Contribution

It proposes a flexible, universal parameterization strategy for GPDs that integrates various data sources and applies to both zero and non-zero skewness regions.

Findings

Successfully fits PDFs, form factors, and lattice GPDs with the parameterization.

Demonstrates quark angular momentum densities and impact parameter distributions.

Shows potential for future experimental data fitting.

Abstract

We present a global analysis program for the generalized parton distributions (GPDs) based on conformal moment expansion. We apply the strategy of universal moment parameterization to fit both the collinear parton distribution functions (PDFs) from phenomenology and generalized form factors from lattice calculations, and show that the parameterization is flexible enough to accommodate these constraints. In addition, we can also fit direct lattice calculations of GPDs from large-momentum effective theory. In this work we focus on the analysis of $t$-dependent PDFs which correspond to GPDs in the $\xi \to 0$ limit. The strategy also applies to the $\xi \not =0$ region with extra parameters, and therefore can be fitted to experimental observables in the future. With a demonstrative example of fitted GPDs, we exhibit the quark transverse angular momentum densities of the proton as well as the impact parameter space distributions of quarks in both unpolarized and transversely polarized protons.