The charge and magnetic radii of the nucleons from the generalized parton distributions

TL;DR

This paper uses a comprehensive analysis of generalized parton distributions to accurately determine the charge and magnetic radii of protons and neutrons, addressing discrepancies in previous measurements and providing consistent results.

Contribution

It introduces a simultaneous global analysis of all experimental data on nucleon radii using GPDs, improving the robustness of radius determinations.

Findings

Proton charge radius: 0.8558 ± 0.0135 fm

Neutron electric radius squared: -0.1181 ± 0.0270 fm²

Neutron magnetic radius: 0.8367 ± 0.0845 fm

Abstract

The proton-radius puzzle refers to the discrepancy observed in measurements of the proton's charge radius when using different methods. This inconsistency has prompted extensive research and debate within the physics community, as it challenges the understanding of quantum electrodynamics and the fundamental properties of protons. In the present study, we determine the charge and magnetic radii of the proton and neutron through a global analysis of the generalized parton distributions (GPDs) at zero skewness. We emphasize the importance of a simultaneous analysis of all available experimental data related to nucleon radii, rather than relying on individual experiments, specific observables, or limited kinematic regions. This comprehensive approach ensures robust and consistent results, avoiding values that are either too small or too large. Our analysis yields the following results: $ r_{pE} = 0.8558 \pm 0.0135~\textrm{fm} $, $ r_{pM} = 0.8268 \pm 0.0533~\textrm{fm} $, $ \left<r_{nE}^2\right> = -0.1181 \pm 0.0270~\textrm{fm}^2 $, and $ r_{nM} = 0.8367 \pm 0.0845~\textrm{fm} $.