The ratio of the proton elastic electromagnetic form factors, ${G}_{\mathit{Ep}}/{G}_{\mathit{Mp}}$, was obtained by measuring ${P}_{t}$ and ${P}_{\ensuremath{\ell}}$, the transverse and longitudinal recoil proton polarization components, respectively, for the elastic $\stackrel{\ensuremath{\rightarrow}}{e}p\ensuremath{\rightarrow}e\stackrel{\ensuremath{\rightarrow}}{p}$reaction in the four-momentum transfer squared range of 0.5 to $3.5\phantom{\rule{0.3em}{0ex}}\text{GeV}{}^{2}$. In the single-photon exchange approximation, ${G}_{\mathit{Ep}}/{G}_{\mathit{Mp}}$ is directly proportional to ${P}_{t}/{P}_{\ensuremath{\ell}}$. The simultaneous measurement of ${P}_{t}$ and ${P}_{\ensuremath{\ell}}$ in a polarimeter reduces systematic uncertainties. The results for ${G}_{\mathit{Ep}}/{G}_{\mathit{Mp}}$ show a systematic decrease with increasing ${Q}^{2}$, indicating for the first time a definite difference in the distribution of charge and magnetization in the proton. The data have been reanalyzed and their systematic uncertainties have become significantly smaller than those reported previously.
Proton elastic form factor ratios toQ2=3.5GeV2by polarization transfer | Litlas
