Coulomb corrections to electron scattering on the extended source and the proton charge radius

Understand

It is shown that the account for the proton charge form factor in the Coulomb corrections to the electron-proton scattering cross section noticeably diminishes the difference between the value of the proton charge radius $r_{\mathrm{E}}$, extracted from the $ep$ scattering data, and that following from the muonic hydrogen data.

• For the electron energy much higher than the electron mass but much smaller than $r_{\mathrm{E}}^{-1}\approx 230$~MeV, the relative correction has the universal form $\delta r_{\mathrm{E}}/r_{\mathrm{E}}=-\pi\alpha/2$, where $\alpha$ is the fine structure constant.