ProtonGE/GMfrom beam-target asymmetry
Citations Over TimeTop 10% of 2006 papers
Abstract
The ratio of the proton's electric to magnetic form factor, ${G}_{E}/{G}_{M}$, can be extracted in elastic electron-proton scattering by measuring cross sections, beam-target asymmetry, or recoil polarization. Separate determinations of ${G}_{E}/{G}_{M}$ by cross sections and recoil polarization observables disagree for ${Q}^{2}>1$ (GeV/$c){}^{2}$. Measurement by a third technique might uncover an unknown systematic error in either of the previous measurements. The beam-target asymmetry has been measured for elastic electron-proton scattering at ${Q}^{2}$ = 1.51 (GeV/$c){}^{2}$ for target spin orientation aligned perpendicular to the beam momentum direction. This is the largest ${Q}^{2}$ at which ${G}_{E}/{G}_{M}$ has been determined by a beam-target asymmetry experiment. The result, $\ensuremath{\mu}{G}_{E}/{G}_{M}=0.884\ifmmode\pm\else\textpm\fi{}0.027\ifmmode\pm\else\textpm\fi{}0.029$, is compared to previous world data.