Updated flexible global parametrization of generalized parton distributions from elastic and deep inelastic inclusive scattering data

TL;DR

This paper introduces an updated, flexible parametrization of generalized parton distributions (GPDs) constrained by high-precision scattering data and lattice QCD calculations, providing detailed forms and form factors relevant for deep virtual Compton scattering.

Contribution

The paper presents a new parametrization of GPDs incorporating recent data and lattice results, with rigorous uncertainty quantification and evolution equations at the initial scale.

Findings

Provides parametric forms of GPDs as functions of x, ξ, t

Includes updated lattice QCD moments in the analysis

Offers predictions for Compton form factors in various kinematic regimes

Abstract

An updated flexible parametrization of the generalized parton distributions in the quark, antiquark and gluon sectors is presented using constraints from high precision electron nucleon deep inelastic scattering data, as well as from the $u$, $d$ quark and gluonic contributions to the nucleon electromagnetic elastic form factors. The latter include recently updated lattice QCD moment calculations. The generalized parton distributions in the vector sector are $H$ and $E$. We rigorously constrain the partonic components, $H_{u_v}$, $H_{d_v}$, $H_{\bar{u}}$, $H_{\bar{d}}$, $H_{\bar{s}}$ and $H_{g}$, and the analogous quantities for $E$, with proper uncertainty quantification. These distributions obey leading order perturbative QCD evolution equations in $\alpha_S$. Parametric forms at the initial scale, $Q_o^2 = 0.58$ $\mathrm{GeV}^2$, for both quarks and gluon distributions are presented as a function of the relevant kinematic variables, namely, the parton momentum fraction, $x$, the skewness, $\xi$, and the invariant, $t$. We also present the Compton form factors entering the deeply virtual Compton scattering process in the kinematic regimes for both fixed target and electron-ion collider settings.