Study of opposite-sign dimuon production in high-energy neutrino-nucleon interactions

Abstract

Results are presented of a study of opposite-sign dimuon events observed in a fine-grained neutrino detector exposed to the Fermilab Tevatron wide-band neutrino beam. A total of 300 background-corrected ${\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$ events induced by incident neutrinos and antineutrinos with energies up to 500 GeV were accumulated. The data were analyzed in terms of a model based on charmquark production followed by semileptonic decay of the charmed meson. The Cabibbo-Kobayashi-Maskawa matrix terms were found to be ${|{U}_{\mathrm{cd}}|}^{2}=0.0378\ifmmode\pm\else\textpm\fi{}0.0127 {(\mathrm{stat})}_{\ensuremath{-}0.0082}^{+0.0099} (\mathrm{syst})$, and $\ensuremath{\kappa}{|{U}_{\mathrm{cs}}|}^{2}=0.391\ifmmode\pm\else\textpm\fi{}0.076 {(\mathrm{stat})}_{\ensuremath{-}0.066}^{+0.097} (\mathrm{syst})$. The ratio of the strange to nonstrange sea in the nucleon, $\ensuremath{\kappa}=\frac{2S}{(\overline{U}+\overline{D})}$, was measured to be 0.407\ifmmode\pm\else\textpm\fi{}0.075 ${(\mathrm{stat})}_{\ensuremath{-}0.069}^{+0.103}$ (syst).