Off the mass shell: Electroweak physics at Nu TeV

The NuTeV collaboration has performed precision measurements of the ratio of neutral current to charged current cross-sections in high rate, high energy neutrino and anti-neutrino beams on a dense, primarily steel, target. The separate neutrino and anti-neutrino beams, high statistics, and improved control of other experimental systematics, allow the determination of electroweak parameters with significantly greater precision than past νN scattering experiments. Our null hypothesis test of the standard model prediction measures sin2 θW(on-shell) = 0.2277 ± 0.0013(stat) ± 0.0009(syst), a value which is 3.0σ above the prediction. We discuss possible explanations for and implications of this discrepancy