1,825 research outputs found

    Study of propellant valve leakage in a vacuum Final summary report

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    Adverse effects of liquid propellant leakage past control valves in vacuum environmen

    The proton and deuteron F_2 structure function at low Q^2

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    Measurements of the proton and deuteron F2F_2 structure functions are presented. The data, taken at Jefferson Lab Hall C, span the four-momentum transfer range 0.06<Q2<2.80.06 < Q^2 < 2.8 GeV2^2, and Bjorken xx values from 0.009 to 0.45, thus extending the knowledge of F2F_2 to low values of Q2Q^2 at low xx. Next-to-next-to-leading order calculations using recent parton distribution functions start to deviate from the data for Q2<2Q^2<2 GeV2^2 at the low and high xx-values. Down to the lowest value of Q2Q^2, the structure function is in good agreement with a parameterization of F2F_2 based on data that have been taken at much higher values of Q2Q^2 or much lower values of xx, and which is constrained by data at the photon point. The ratio of the deuteron and proton structure functions at low xx remains well described by a logarithmic dependence on Q2Q^2 at low Q2Q^2.Comment: 3 figures, submitted pape

    Measurement of the lifetime of the B_c meson in the semileptonic decay channel

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    Using approximately 1.3 fb-1 of data collected by the D0 detector between 2002 and 2006, we measure the lifetime of the B_c meson in the B_c -> J/psi mu nu X final state. A simultaneous unbinned likelihood fit to the J/\psi+mu invariant mass and lifetime distributions yields a signal of 881 +/- 80 (stat) candidates and a lifetime measurement of \tau(B_c) = 0.448 +0.038 -0.036 (stat) +/- 0.032 (syst) ps.Comment: 7 pages, 2 figures, submitted to Phys. Rev. Let

    Measurement of the W boson mass

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    We present a measurement of the W boson mass in W -> ev decays using 1 fb^-1 of data collected with the D0 detector during Run II of the Fermilab Tevatron collider. With a sample of 499830 W -> ev candidate events, we measure M_W = 80.401 +- 0.043 GeV. This is the most precise measurement from a single experiment.Comment: As published in PR

    Double parton interactions in photon+3 jet events in ppbar collisions sqrt{s}=1.96 TeV

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    We have used a sample of photon+3 jets events collected by the D0 experiment with an integrated luminosity of about 1 fb^-1 to determine the fraction of events with double parton scattering (f_DP) in a single ppbar collision at sqrt{s}=1.96 TeV. The DP fraction and effective cross section (sigma_eff), a process-independent scale parameter related to the parton density inside the nucleon, are measured in three intervals of the second (ordered in pT) jet transverse momentum pT_jet2 within the range 15 < pT_jet2 < 30 GeV. In this range, f_DP varies between 0.23 < f_DP < 0.47, while sigma_eff has the average value sigma_eff_ave = 16.4 +- 0.3(stat) +- 2.3(syst) mb.Comment: 15 pages, 13 figure

    Search for new fermions ("quirks") at the Fermilab Tevatron Collider

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    We report results of a search for particles with anomalously high ionization in events with a high transverse energy jet and large missing transverse energy in 2.42.4 fb1^{-1} of integrated luminosity collected by the D0 experiment at the Fermilab Tevatron ppˉp\bar{p} collider. Production of such particles (quirks) is expected in scenarios with extra QCD-like {\it SU(N)} sectors, and this study is the first dedicated search for such signatures. We find no evidence of a signal and set a lower mass limit of 107 ~GeV for the mass of a charged quirk with strong dynamics scale Λ\Lambda in the range from 10 keV to 1 MeV.Comment: submitted to Phys. Rev. Letter

    b-Jet Identification in the D0 Experiment

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    Algorithms distinguishing jets originating from b quarks from other jet flavors are important tools in the physics program of the D0 experiment at the Fermilab Tevatron p-pbar collider. This article describes the methods that have been used to identify b-quark jets, exploiting in particular the long lifetimes of b-flavored hadrons, and the calibration of the performance of these algorithms based on collider data.Comment: submitted to Nuclear Instruments and Methods in Physics Research

    Observation of ZZ production in ppbar collisions at sqrt(s) = 1.96 TeV

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    We present an observation for ZZ -> l+l-l'+l'- (l, l' = e or mu) production in ppbar collisions at a center-of-mass energy of sqrt(s) = 1.96 TeV. Using 1.7 fb-1 of data collected by the D0 experiment at the Fermilab Tevatron Collider, we observe three candidate events with an expected background of 0.14 +0.03 -0.02 events. The significance of this observation is 5.3 standard deviations. The combination of D0 results in this channel, as well as in ZZ -> l+l-nunubar, yields a significance of 5.7 standard deviations and a combined cross section of sigma(ZZ) = 1.60 +/- 0.63 (stat.) +0.16 -0.17 (syst.) pb.Comment: 7 pages, 1 figure, 2 tables Modified slightly following review proces
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