Measurement of the neutral-current-to-charged-current cross-section ratio for antineutrino-proton inclusive scattering

The Fermilab wide-band antineutrino beam incident on the hydrogen-filled 15-foot bubble chamber was used to study nu-barp neutral-current interactions. The u = x(1-y) distribution is presented for both the neutral- and the charged-current data sample. Fitting the neutral-current u distribution to the prediction of a simple quark-parton model measures the Weinberg angle. By using recent measurements of the neutral-to-charged-current cross-section ratio for ..nu..p interactions (R/sub p/), we find the corresponding ratio for nu-barp interactions (R-bar/sub p/) to be 0.36 +- 0.06.