We have measured the parity-violating electroweak asymmetry in the elastic scattering of polarized electrons from the proton. The result is A = -15.05 ± 0.98(stat) ± 0.56(syst) ppm at the kinematic point (θlab) = 12.3° and (Q2) = 0.477 (Ge V/c)2. Both errors are a factor of two smaller than those of the result reported previously. The value for the strange form factor extracted from the data is (GS E + 0.392 GS M) = 0.025 ± 0.020 ± 0.014, where the first error is experimental and the second arises from the uncertainties in electromagnetic form factors. This measurement is the first fixed-target parity violation experiment that used either a "strained" GaAs photocathode to produce highly polarized electrons or a Compton polarimeter to continuously monitor the electron beam polarization.
|Original language||English (US)|
|Number of pages||6|
|Journal||Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics|
|State||Published - Jul 14 2001|
ASJC Scopus subject areas
- Nuclear and High Energy Physics