We present measurements of the semi-inclusive cross sections for νμ- and ν¯μ-nucleon deep inelastic scattering interactions with two oppositely charged muons in the final state. These events dominantly arise from the production of a charm quark during the scattering process. The measurement was obtained from the analysis of 5102 νμ-induced and 1458 ν¯μ-induced events collected with the NuTeV detector exposed to a sign-selected beam at the Fermilab Tevatron. We also extract a cross-section measurement from a reanalysis of 5030 νμ-induced and 1060 ν¯μ-induced events collected from the exposure of the same detector to a quad-triplet beam by the Chicago Columbia Fermilab Rochester (CCFR) experiment. The results are combined to obtain the most statistically precise measurement of neutrino-induced dimuon production cross sections to date. These measurements should be of broad use to phenomenologists interested in the dynamics of charm production, the strangeness content of the nucleon, and the Cabibbo-Kobayashi-Maskawa matrix element Vcd.
We present a new measurement of the difference between the nucleon strange and antistrange quark distributions from dimuon events recorded by the NuTeV experiment at Fermilab. This analysis is the first to use a complete next to leading order QCD d escription of charm production from neutrino scattering. Dimuon events in neutrino deep inelastic scattering allow direct and independent study of the strange and antistrange content of the nucleon. We find a positive strange asymmetry with a significance of 1.6sigma . We also report a new measurement of the charm mass.
Using a silicon-microstrip detector array to identify secondary vertices occurring downstream of a short platinum target, we have searched for the decay D0→μ+μ−. Normalized relative to the J/ψ→μ+μ− signal observed in the same data sample, for a 3.25-mm minimum decay distance our branching-ratio sensitivity is (4.8±1.4)×10−6 per event, and after background subtraction we observe -4.1±4.8 events. Using the statistical approach advocated by the Particle Data Group, we obtain a limit B(D0→μ+μ−)<3.1×10−5 at 90% confidence, confirming with a different technique the limit previously obtained by Louis et al. The interpretation of the upper limit involves complex statistical issues; we present another approach which is more suitable for combining the results of different experiments.
A precise measurement of the ratio of Drell-Yan yields from an 800 GeV/c proton beam incident on hydrogen and deuterium targets is reported. Over 140,000 Drell-Yan muon pairs with dimuon mass M_{mu+ mu-} >= 4.5 GeV/c^2 were recorded. From these data, the ratio of anti-down (dbar) to anti-up (ubar) quark distributions in the proton sea is determined over a wide range in Bjorken-x. A strong x dependence is observed in the ratio dbar/ubar, showing substantial enhancement of dbar with respect to ubar for x<0.2. This result is in fair agreement with recent parton distribution parameterizations of the sea. For x>0.2, the observed dbar/ubar ratio is much nearer unity than given by the parameterizations.
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