On the Effect of Asymmetric Strange Seas and Isospin-Violating Parton   Distribution Functions on sin2thetaW Measured at NuTeV
  The NuTeV collaboration recently reported a value of sin2thetaW measured in neutrino-nucleon scattering that is 3 standard deviations above the standard model prediction. This result is derived assuming that (1) the strange sea is quark-antiquark symmetric, s(x)=sbar(x), and (2) up and down quark distributions are symmetric under the simultaneous interchange of u<->d and p<->n. We report the impact of violations of these symmetries on sin2thetaW and discuss the theoretical and experimental constraints on such asymmetries. 
NuTeV Collaboration: G.P. Zeller, K.S. McFarland, et al