Generalized parton distributions at zero skewness

We present a new determination of the generalized parton distributions (GPDs) with their uncertainties at zero skewness, & xi; = 0, through a simultaneous analysis of all available experimental data of the nucleon electromagnetic form factors (FFs), nucleon charge and magnetic radii, proton axial FFs (AFFs), and wide-angle Compton scattering (WACS) cross sections for the first time, and we investigate whether there is any tension between these data. This can be considered the most comprehensive analysis of GPDs at & xi; = 0 performed so far. We show that such an analysis provides the simultaneous determination of three kinds of GPDs: namely Hq, & SIM;Hq, and Eq, considering also the sea-quark contributions. As a result, we find that the inclusion of the WACS and AFF data at larger values of the momentum transfer squared Q2 = -t can put new constraints on GPDs and change them drastically in some cases. We show that there is a considerable tension between the WACS and the proton magnetic form factor (GpM) data, especially at larger values of -t. However, we indicate that the results for the gravitational FF M2 and the proton total angular momentum Jp calculated using the extracted GPDs are in relatively good agreement with the light-cone QCD sum rules (LCSRs) and lattice QCD predictions when the sea-quark contributions are considered and both WACS and GpM data are included in the analyses simultaneously.

Automated summary

In this study, a comprehensive analysis of various experimental data, including nucleon electromagnetic form factors, nucleon charge and magnetic radii, proton axial form factors, and wide-angle Compton scattering cross sections, is conducted to determine the generalized parton distributions (GPDs) at zero skewness, xi=0. Three types of GPDs, namely Hq, SIM;Hq, and Eq, are simultaneously determined, taking into account the contributions of sea quarks. The results reveal significant tensions between the wide-angle Compton scattering and proton magnetic form factor data, especially at larger values of -t. However, when sea quark contributions are considered and both wide-angle Compton scattering and proton magnetic form factor data are included in the analyses simultaneously, the extracted GPDs show relatively good agreement with the light-cone QCD sum rules and lattice QCD predictions.