Measurement of neutrino-proton and antineutrino-proton elastic scattering

Reported here are new measurements of neutrino-proton and antineutrino-proton elastic scattering, performed in the BNL neutrino beam with a segmented liquid scintillator calorimeter target-detector. Observed is a net signal of 108 neutrino events and 83 antineutrino events which, combined with earlier results, lead to determination of the values R/sub nu/ == sigma(nu/sub μ/ + p → nu/sub μ/ + p) / sigma(nu/sub μ/ + n → anti μ + p) = 0.11 +- 0.015, R/sub anti nu/ == sigma(anti nu/sub μ/ + p → anti nu/sub μ/ + p) / sigma(anti nu/sub μ/ + p → μ+ + n) = 0.19 +- 0.035, and R/sup NC/ == sigma(anti nu/sub μ/ + p → anti nu/sub μ/ + p) / sigma(nu/sub μ/ + p → nu/sub μ/ + p) = 0.41 +- 0.09 for 0.40 < Q2 < 0.90 (GeV/c)2 where -Q2 is the square of the momentum transfer to the nucleon. The differential cross sections as functions of Q2, dsigma/sup nu//dQ2 and dsigma/sup anti nu//dQ2 are also determined. Our results are in good agreement with the WS-GIM model of the weak and electromagnetic interactions and yield sin2theta/sub w/ = 0.28 +- 0.03