The ratio of the proton's elastic electromagnetic form factors, ${G}_{{E}_{p}}{/G}_{{M}_{p}}$, was obtained by measuring ${P}_{t}$ and ${P}_{\ensuremath{\ell}}$, the transverse and the longitudinal recoil proton polarization, respectively. For elastic $\stackrel{\ensuremath{\rightarrow}}{e}p\ensuremath{\rightarrow}e\stackrel{\ensuremath{\rightarrow}}{p}$, ${G}_{{E}_{p}}{/G}_{{M}_{p}}$ is proportional to ${P}_{t}{/P}_{\ensuremath{\ell}}$. Simultaneous measurement of ${P}_{t}$ and ${P}_{\ensuremath{\ell}}$ in a polarimeter provides good control of the systematic uncertainty. The results for the ratio ${G}_{{E}_{p}}{/G}_{{M}_{p}}$ show a systematic decrease as ${Q}^{2}$ increases from 0.5 to $3.5{\mathrm{GeV}}^{2}$, indicating for the first time a definite difference in the spatial distribution of charge and magnetization currents in the proton.
GEp/GMpRatio by Polarization Transfer ine→p→ep→ | Litlas
