Coulomb corrections to elastic electron–proton scattering and the proton charge radius

Recent values of the proton charge radius derived from the Lamb shift in electronic hydrogen tend to be larger than those from electron scattering. Therefore low-momentum-transfer scattering data from different experiments have been reanalyzed with Coulomb and recoil corrections included. This was done by calculating at each scattering angle and scattering energy the corresponding correction obtained from a partial wave program which includes recoil approximately. Corrections due to magnetic scattering were also made before the rms-radius was determined by a fit which allows free normalization for each experiment. It is shown that the inclusion of Coulomb corrections in the analysis of electron scattering data lowers the χ2 of the fit and increases the proton radius by about (0.008–0.013) fm depending on the fit strategy. A value of rp=0.880 (15) fm is obtained which is in good agreement with the one extracted from Lamb shift measurements.