Proton charge and magnetic rms radii from the elastic $ep$ scattering data

TL;DR

This paper analyzes elastic electron-proton scattering data to accurately determine proton charge and magnetic radii, accounting for statistical and systematic errors, and emphasizes the importance of two-photon exchange corrections.

Contribution

It provides new measurements of proton charge and magnetic radii with combined statistical and systematic errors, including the impact of form factor parameterization and two-photon exchange corrections.

Findings

r_E = 0.912 ± 0.009 (stat) ± 0.007 (syst) fm

r_M = 0.876 ± 0.010 (stat) ± 0.016 (syst) fm

Two-photon exchange corrections improve fit quality and radii estimates.

Abstract

The elastic electron-proton scattering data are analysed in order to determine proton charge and magnetic rms radii, r_E and r_M. Along with the usual statistical error, we try to estimate a systematic error in the radii, caused by the inadequacy of particular form factor parameterization employed. The range of data to use in the analysis is chosen so as to minimize the total (statistical + systematic) error. We obtain r_E = 0.912 +- 0.009 (stat) +- 0.007 (syst) fm, and r_M = 0.876 +- 0.010 (stat) +- 0.016 (syst) fm. The cross-section data were corrected for two-photon exchange. We found that without such corrections obtained r_E and r_M are somewhat smaller while the quality of fit is worse.