Measurement of the strange sea distribution using neutrino charm production

A high-statistics study by the Columbia-Chicago-Fermilab-Rochester Collaboration of opposite-sign dimuon events induced by neutrino-nucleon scattering at the Fermilab Tevatron is presented. A sample of 5044 ${\nu }_{\mathrm{\mu }}$ and 1062 ν${\mathrm{¯}}_{\mathrm{\mu }}$ induced ${\mathrm{\mu }}^{\mp }$ ${\mathrm{\mu }}^{\pm }$ events with ${\mathit{P}}_{\mathrm{\mu }1}$≥9 GeV/c, ${\mathit{P}}_{\mathrm{\mu }2}$≥5 GeV/c, 30≤${\mathit{E}}_{\nu }$≤600 GeV, and 〈${\mathit{Q}}^2$〉=22.2 ${\mathrm{GeV}}^2$/${\mathit{c}}^2$ is observed. The data support the slow-rescaling model of charm production with a value of ${\mathit{m}}_{\mathit{c}}$=1.31±0.24 ${\mathrm{GeV}}^2$/${\mathit{c}}^2$. The first measurement of the ${\mathit{Q}}^2$ dependence of the nucleon strange quark distribution xs(x) is presented. The data yield the Cabibbo-Kobayashi-Maskawa matrix element ‖${\mathit{V}}_{\mathit{c}\mathit{d}}$‖=0.209±0.012 and the nucleon fractional strangeness content ${\mathrm{\eta }}_{\mathit{s}}$=0.${064}_{\mathrm{-}0.007}^{+0.008\mathrm{}}$.