Early Analysis of the SBS GEp-V Proton Form Factor Measurement at Jefferson Lab

The Jefferson Lab Hall A Super Bigbite Spectrometer (SBS) experimental program was developed with the goal of making precision measurements of the nucleon elastic electromagnetic form factors. In particular, SBS experiment E12-07-109 (GEp-V) measures the proton electromagnetic form factor ratio G_E^P/G_M^P, extending the range of data to high momentum transfer Q² with unprecedented precision. GEp-V uses the recoil polarization technique in which a longitudinally polarized electron beam is scattered off a fixed unpolarized proton target. The resulting transfer of polarization to the recoiling proton is measured by a spin-dependent secondary scattering process in a CH₂ analyzer block, which manifests itself as a helicity asymmetry in the azimuthal distribution of the scattered protons. Finally, the ratio of the longitudinal and perpendicular polarization components is directly proportional to the form factor ratio. GEp-V ran during the summer of 2025 and data is currently being analyzed. The progress on some of these analysis efforts will be presented.