Generalized parton distributions of the proton from lattice QCD

TL;DR

This paper computes the isovector generalized parton distributions of the proton using lattice QCD with twisted mass fermions, providing insights into the proton's internal structure through first-principles calculations.

Contribution

It introduces lattice QCD calculations of GPDs using the quasi-distribution formal on a specific ensemble, including unpolarized, helicity, and transversity GPDs at various skewness values.

Findings

Results show qualitative agreement with model predictions.

GPDs are computed with controlled statistical uncertainties.

Provides first-principles insights into proton structure.

Abstract

Generalized parton distributions (GPDs) are among the most fundamental quantities for describing the internal structure of hadrons. In this work, we present results on isovector GPDs of the proton obtained within lattice Quantum Chromodynamics. We use the quasi-distribution formalism and perform the calculations on an ensemble of $N_f = 2 + 1 + 1$ twisted mass fermions, with pion mass $M_\pi=260$~MeV and lattice spacing $a\simeq 0.093$~fm. Results are presented for unpolarized, helicity, and transversity GPDs at zero and nonzero skewness with controlled statistical uncertainties. Comparisons with their forward limit show qualitative features anticipated from model calculations.