Precise Determination of Electroweak Parameters in NeutrinoNucleon Scattering.pdf

Shadowing Corrections and the Precise Determination of Electroweak Parameters in Neutrino-Nucleon Scattering Gerald A. Miller University of Washington Seattle, WA 98195-1560 A. W. Thomas Department of Physics and Mathematical Physics, and Special Research Centre for the Subatomic Structure of Matter Univ. of Adelaide, Adelaide 5005, Australia 4 0 0 2 2 A systematic error in the extraction of sin θW from nuclear deep inelastic scat- l tering of neutrinos and antineutrinos arises from higher-twist effects arising from u nuclear shadowing. We explain that these effects cause a correction to the results J 9 of the recently reported significant deviation from the Standard Model that is po- tentially as large as the deviation claimed, and of a sign that cannot be determined 3 without an extremely careful study of the data set used to model the input parton v 7 distribution functions. 0 In a recent and stimulating paper [1], the NuTeV collaboration reported a determination of 0 2 4 sin θW , based on a comparison of charged and neutral current neutrino interactions with a nuclear 0 target (Fe), which differs from the Standard Model prediction by three standard deviations. In view 2 0 of the importance of such a result it is vital that the sources of systematic error be clearly identified / and examined. Here we explain