Andrew O. Bazarko

Determination of the strange quark content of the nucleon from a next-to-leading order QCD analysis of neutrino charm production

AbstractWe present the first next-to-leading-order QCD analysis of neutrino charm production, using a sample of 6090νμ− and

Further Evidence for the DecayK+→π+νν¯

\bar \nu _\mu

F_2

-induced opposite-sign dimuon events observed in the CCFR detector at the Fermilab Tevatron. We find that the nucleon strange quark content is suppressed with respect to the non-strange sea quarks by a factor κ=0.477−0.053+0.063, where the error includes statistical, systematic and QCD scale uncertainties. In contrast to previous leading order analyses, we find that the strange seax-dependence is similar to that of the non-strange sea, and that the measured charm quark mass,mc=1.70±0.19 GeV/c2, is larger and consistent with that determined in other processes. Further analysis finds that the difference inx-distributions betweenxs(x) and

xF^{\nu}_3 - x F^{\bar{\nu}}_3

x\bar s{\text{(}}x{\text{)}}

\nu_\mu-

is small. A measurement of the Cabibbo-Kobayashi-Maskawa matrix element |Vcd|=0.232−0.020+0.018 is also presented.

Fe and

Additional evidence for the rare kaon decay K+ to pi+ neutrino-antineutrino has been found in a new data set with comparable sensitivity to the previously reported result. One new event was observed in the pion momentum region examined, 211<P<229 MeV/c, bringing the total for the combined data set to two. Including all data taken, the backgrounds were estimated to contribute 0.15 pm 0.05 events. The branching ratio is B=1.57^{+1.75}_{-0.82} 10^{-10}.