Lawrence Berkeley National Laboratory

Abstract. The CCFR collaboration reports a precise measurement of electroweak parameters derived from the ratio of neutral-current to charged-current cross-sections in neutrino-nucleon scattering at the Fermilab Tevatron. We determine $$\sin^2\theta_W^{\rm \scriptstyle (on-shell)}=0.2236\pm0.0028{\rm\textstyle (expt.)}\pm0.0030{\rm\textstyle (model)}$$ for $$M_{\rm \scriptstyle top}=175$$ GeV, $$M_{\rm \scriptstyle Higgs}=150$$ GeV. This is equivalent to $$M_W=80.35\pm0.21$$ GeV. The good agreement of this measurement with Standard Model expectations implies the exclusion of additional $$ u u qq$$ contact interactions at 95% confidence at a mass scale of 1-8 TeV, depending on the form of the contact interaction.