Model-independent extraction of the proton charge radius from electron scattering

Publisher Website
Google Scholar
Abstract
Constraints from analyticity are combined with experimental electron-proton scattering data to determine the proton charge radius. In contrast to previous determinations, we provide a systematic procedure for analyzing arbitrary data without model-dependent assumptions on the form-factor shape. We also investigate the impact of including electron-neutron scattering data, and $\pi${}$\pi${}$\rightarrow${}NN\ifmmode\bar\else\textasciimacron\fi{} data. Using representative data sets we find rEp=0.870\ifmmode\pm\else\textpm\fi{}0.023\ifmmode\pm\else\textpm\fi{}0.012\,\,fm using just proton scattering data; rEp=0.880-0.020+0.017\ifmmode\pm\else\textpm\fi{}0.007\,\,fm adding neutron data; and rEp=0.871\ifmmode\pm\else\textpm\fi{}0.009\ifmmode\pm\else\textpm\fi{}0.002\ifmmode\pm\else\textpm\fi{}0.002\,\,fm adding $\pi${}$\pi${} data. The analysis can be readily extended to other nucleon form factors and derived observables.