We have measured the parity-violating electroweak asymmetry in the elastic scattering of polarized electrons from the proton. The kinematic point [〈θlab〉 = 12.3° and (Q2) = 0.48 (GeV/c)2] is chosen to provide sensitivity, at a level that is of theoretical interest, to the strange electric form factor Gs E. The result, A = -14.5 ± 2.2 ppm, is consistent with the electroweak standard model and no additional contributions from strange quarks. In particular, the measurement implies Gs E + 0.39 Gs M = 0.023 ± 0.034(stat) ± 0.022(syst) ± 0.026(δGn E), where the last uncertainty arises from the estimated uncertainty in the neutron electric form factor.
|Original language||English (US)|
|Number of pages||5|
|Journal||Physical Review Letters|
|State||Published - Feb 8 1999|
ASJC Scopus subject areas
- Physics and Astronomy(all)