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 $\overline{\nu }p$ neutral-current interactions. The $u=x(1-y)\mathrm{}$ 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 ($R_p$), we find the corresponding ratio for $\overline{\nu }p$ interactions (${\overline{R}}_p$) to be 0.36±0.06.