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 $\pi\pi\to N\bar{ N}$ data. Using representative datasets we find r_E^p=0.870 +/- 0.023 +/- 0.012 fm using just proton scattering data; r_E^p=0.880^{ +0.017}_{ -0.020} +/- 0.007 fm adding neutron data; and r_E^p=0.871 +/- 0.009 +/- 0.002 +/- 0.002 fm adding $\pi\pi$ data. The analysis can be readily extended to other nucleon form factors and derived observables.
Categories: hep-ph nucl-ex nucl-th physics.atom-ph