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

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 μ⁺μ^- 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 charm-quark production followed by semileptonic decay of the charmed meson. The Cabibbo-Kobayashi-Maskawa matrix terms were found to be ||U_cd||²=0.0378+/-0.0127 (stat)^+0.0099_-0.0082 (syst), and κ||U_cs||²=0.391+/-0.076 (stat)^+0.097_-0.066 (syst). The ratio of the strange to nonstrange sea in the nucleon, κ=2S/(U¯+D¯), was measured to be 0.407+/-0.075 (stat)^+0.103_-0.069 (syst).