926 research outputs found

    Measurement of the ratio of inclusive cross sections σ(ppˉZ+2 bjets)/σ(ppˉZ+2 jets)\sigma (p\bar{p} \rightarrow Z+2~b \text{jets}) / \sigma (p\bar{p} \rightarrow Z+ \text{2 jets}) in ppˉp\bar{p} collisions at s=1.96\sqrt s=1.96 TeV

    Get PDF
    We measure the ratio of cross sections, σ(ppˉZ+2 b jets)\sigma(p\bar{p}\rightarrow Z+2~b~\text{jets})/σ(ppˉZ+2 jets)\sigma(p\bar{p}\rightarrow Z+\text{2 jets}), for associated production of a ZZ boson with at least two jets with transverse momentum pTjet>20p_T^{\rm jet} > 20 GeV and pseudorapidity ηjet<2.5|\eta^{\rm jet}| < 2.5. This measurement uses data corresponding to an integrated luminosity of 9.7 fb1^{-1} collected by the \DO experiment in Run II of Fermilab's Tevatron \ppbar Collider at a center-of-mass energy of 1.96 TeV. The measured integrated ratio of 0.0236\pm0.0032\left(\mbox{stat}\right)\pm0.0035\left(\mbox{syst}\right) is in agreement with predictions from next-to-leading-order perturbative QCD and the Monte Carlo event generators {\sc pythia} and {\sc alpgen}

    Precision measurement of the top-quark mass in lepton+jets final states

    Get PDF
    We measure the mass of the top quark in lepton++jets final states using the full sample of ppˉp\bar{p} collision data collected by the D0 experiment in Run II of the Fermilab Tevatron Collider at s=1.96\sqrt s=1.96 TeV, corresponding to 9.7fb19.7 {\rm fb}^{-1} of integrated luminosity. We use a matrix element technique that calculates the probabilities for each event to result from ttˉt\bar t production or background. The overall jet energy scale is constrained in situ by the mass of the WW boson. We measure mt=174.98±0.76m_t=174.98\pm0.76 GeV. This constitutes the most precise single measurement of the top-quark mass.Comment: submitted to Phys. Rev. D, 40 pages, detailed documentation of Phys. Rev. Lett. 113, 032002 (2014) [arXiv:1405.1756

    Improved bb quark jet identification at the D0 experiment

    Full text link
    The ability to identify jets which originated from bb quarks is an important tool of the physics program of the D0 experiment at the Fermilab Tevatron ppˉp\bar{p} collider. This article describes a new algorithm designed to select jets originating from bb quarks while suppressing the contamination caused by jets from other quark flavors and gluons. Additionally, a new technique, the SystemN method, for determining the misidentification rate directly from data is presented.Comment: Submitted to Nucl. Instrum. Methods Phys. Res.

    Measurement of the differential γ+2 b\gamma+2~b-jet cross section and the ratio σ\sigma(γ+2 b\gamma+2~b-jets)/σ\sigma(γ+b\gamma+b-jet) in ppˉp\bar{p} collisions at s\sqrt{s}=1.96 TeV

    Get PDF
    We present the first measurements of the differential cross section dσ/dpTγd\sigma/dp_{T}^{\gamma} for the production of an isolated photon in association with at least two bb-quark jets. The measurements consider photons with rapidities yγ<1.0|y^\gamma| < 1.0 and transverse momenta 30<pTγ1530 < p_{T}^{\gamma} 15 GeV and yjet<1.5| y^{jet}| < 1.5. The ratio of differential production cross sections for γ+2 b\gamma+2~b-jets to γ+b\gamma+b-jet as a function of pTγp_{T}^{\gamma} is also presented. The results are based on the proton-antiproton collision data at s=\sqrt{s}=1.96~\TeV collected with the D0 detector at the Fermilab Tevatron Collider. The measured cross sections and their ratios are compared to the next-to-leading order perturbative QCD calculations as well as predictions based on the kTk_{T}-factorization approach and those from the SHERPA and PYTHIA Monte Carlo event generators.Comment: 10 pages, 8 figures, Submitted to Phys. Lett.

    Measurement of the ϕη\phi^*_\eta distribution of muon pairs with masses between 30 and 500 GeV in 10.4 fb1^{-1} of ppˉp\bar{p} collisions

    Get PDF
    We present a measurement of the distribution of the variable ϕη\phi^*_\eta for muon pairs with masses between 30 and 500 GeV, using the complete Run II data set collected by the D0 detector at the Fermilab Tevatron proton-antiproton collider. This corresponds to an integrated luminosity of 10.4 fb1^{-1} at s\sqrt{s} = 1.96 TeV. The data are corrected for detector effects and presented in bins of dimuon rapidity and mass. The variable ϕη\phi^*_\eta probes the same physical effects as the Z/γZ/\gamma^* boson transverse momentum, but is less susceptible to the effects of experimental resolution and efficiency. These are the first measurements at any collider of the ϕη\phi^*_\eta distributions for dilepton masses away from the Z+Z\rightarrow \ell^+\ell^- boson mass peak. The data are compared to QCD predictions based on the resummation of multiple soft gluons.Comment: Accepted for publication in Phys.Rev.