2,413 research outputs found

    CMS Use of a Data Federation

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    CMS is in the process of deploying an Xrootd based infrastructure to facilitate a global data federation. The services of the federation are available to export data from half the physical capacity and the majority of sites are configured to read data over the federation as a back-up. CMS began with a relatively modest set of use-cases for recovery of failed local file opens, debugging and visualization. CMS is finding that the data federation can be used to support small scale analysis and load balancing. Looking forward we see potential in using the federation to provide more flexibility in the location workflows are executed as the difference between local access and wide area access are diminished by optimization and improved networking. In this presentation we discuss the application development work and the facility deployment work, the use-cases currently in production, and the potential for the technology moving forward

    CMS Use of a Data Federation

    Get PDF
    CMS is in the process of deploying an Xrootd based infrastructure to facilitate a global data federation. The services of the federation are available to export data from half the physical capacity and the majority of sites are configured to read data over the federation as a back-up. CMS began with a relatively modest set of use-cases for recovery of failed local file opens, debugging and visualization. CMS is finding that the data federation can be used to support small scale analysis and load balancing. Looking forward we see potential in using the federation to provide more flexibility in the location workflows are executed as the difference between local access and wide area access are diminished by optimization and improved networking. In this presentation we discuss the application development work and the facility deployment work, the use-cases currently in production, and the potential for the technology moving forward

    Evidence for the Exclusive Decay \u3ci\u3eB\u3c/i\u3e\u3csub\u3e\u3ci\u3ec\u3c/i\u3e\u3c/sub\u3e\u3csup\u3e±\u3c/sup\u3e → \u3ci\u3eJ\u3c/i\u3e/ψπ\u3csup\u3e±\u3c/sup\u3e and Measurement of the Mass of the \u3ci\u3eB\u3c/i\u3e\u3csub\u3e\u3ci\u3ec\u3c/i\u3e\u3c/sub\u3e\u3csup\u3e±\u3c/sup\u3e Meson

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    We report the first evidence for a fully reconstructed decay mode of the Bc± meson in the channel Bc± → J/ψπ±, with J/ψ → μ+ μ-. The analysis is based on an integrated luminosity of 360 pb-1 in pp̅ collisions at 1.96 TeV center of mass energy collected by the Collider Detector at Fermilab. We observe 14.6 ± 4.6 signal events with a background of 7.1 ± 0.9 events, and a fit to the J/ ψπ± mass spectrum yields a Bc± mass of 6285.7 ± 5.3(stat) ± 1.2(syst) MeV/c2. The probability of a peak of this magnitude occurring by random fluctuation in the search region is estimated as 0.012%

    Measurement of the azimuthal angle distribution of leptons from\u3ci\u3eW\u3c/i\u3e boson decays as a function of the \u3ci\u3eW\u3c/i\u3e transverse momentum in \u3ci\u3epp̅\u3c/i\u3e collisions at √s = 1.8 TeV

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    We present the first measurement of the A2 and A3 angular coefficients of the W boson produced in proton-antiproton collisions. We study W → e νe and W → e νe candidate events produced in association with at least one jet at CDF, during Run Ia and Run Ib of the Tevatron at √s =1:8 TeV. The corresponding integrated luminosity was 110 pb-1. The jet balances the transverse momentum of the W and introduces QCD effects in W boson production. The extraction of the angular coefficients is achieved through the direct measurement of the azimuthal angle of the charged lepton in the Collins-Soper rest-frame of the W boson. The angular coefficients are measured as a function of the transverse momentum of the W boson. The electron, muon, and combined results are in good agreement with the standard model prediction, up to order αs2 in QCD

    Measurement of the mass splittings between the \u3ci\u3ebb̅\u3c/i\u3eχ\u3csub\u3eb,J\u3c/sub\u3e(1\u3ci\u3eP\u3c/i\u3e) states

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    We present new measurements of photon energies and branching fractions for the radiative transitions Υ(2S) → γχb(J=0,1,2)(1P). The masses of the χb states are determined from the measured radiative photon energies. The ratio of mass splittings between the χb substates, r ≡ [(MJ=2 -MJ=1)/( MJ=1 - MJ=0), with M the χb mass, provides information on the nature of the bb̅ confining potential. We find r(1P)=0.542 ±0.022±0.024. This value is somewhat lower than the previous world average, but more consistent with the theoretical expectation that r(1P) \u3c r(2P); i.e., that this mass splitting ratio is smaller for the χb (1P) states than for the χb (2P) states

    Evidence for \u3ci\u3eB\u3c/i\u3e\u3csup\u3e0\u3c/sup\u3e → ρ\u3csup\u3e0\u3c/sup\u3e ρ\u3csup\u3e0\u3c/sup\u3e Decays and Implications for the Cabibbo-Kobayashi-Maskawa Angle α

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    We search for the decays B0 → ρ0 ρ0, B0 → ρ0f0(980), and B0 → f0(980)f0(980) in a sample of about 384 × 106 Υ (4S)→ BB̅ decays collected with the BABAR detector at the PEP-II asymmetric-energy ℯ+ ℯ- collider at Stanford Linear Accelerator Center. We find evidence for B0 → ρ0 ρ0 with 3.5σ significance and measure the branching fraction Ɓ = 1.07 ± 0:33 ± 0:19) × 10-6 and longitudinal polarization fraction fL = 0.87 ± 0.13 ± 0.04, where the first uncertainty is statistical, and the second is systematic. The uncertainty on the Cabibbo-Kobayashi-Maskawa quark-mixing matrix unitarity angle α due to penguin contributions in B→ ρρ decays is 18° at the 1σ level. We also set upper limits on the B0 → ρ0f0(980) and i\u3eB0 → f0(980)f0(980) decay rates

    Hadronic transitions Υ(2\u3ci\u3eS\u3c/i\u3e)→Υ(1\u3ci\u3eS\u3c/i\u3e)

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    Using a 73.6 pb-1 data sample of Υ(2S) events collected with the CLEO II detector at the Cornell Electron Storage Ring, we have investigated the hadronic transitions between the Υ(2S) and the Υ(1S). The dipion transition Υ(2S) → Υ(1S) π+π- was studied using two different analysis techniques. Selecting events in which Υ(1S) → e+e-, μ+μ- (‘‘exclusive’’ analysis), and using the Υ(1S) leptonic branching fractions world averages from the PDG review, we obtained Ɓ(Υ(2S) → Υ(1S) π+π-) =0.189±0.004±0.010, while using a method allowing Υ(1S) → anything (‘‘inclusive’’ analysis) we obtained Ɓ(Υ(2S) → Υ(1S) π+π-) = 0.196 ±0.002±0.010. The appropriate weighted average of the two measurements gives Ɓ(Υ(2S) → Υ(1S) π+π-) = 0.192±0.002±0.010. Combining the exclusive and inclusive results we derive the Υ(1S) leptonic branching fractions Bee = 0.0229±0.0008±0.0011 and Bμμ = 0.0249±0.0008±0.0013. We also studied Υ(2S) → Υ(1S) π0π0 and obtained Ɓ(Υ(2S) → Υ(1S) π0π0) = 0.092±0.006±0.008. Parameters of the π π system (dipion invariant mass spectra, angular distributions) were analyzed and found to be consistent with current theoretical models. Lastly, we searched for the η and single π0 transitions and obtained the 90% confidence level upper limits Ɓ(Υ(2S) → Υ(1S) η) \u3c 0.0028 and Ɓ(Υ(2S) → Υ(1S) π0) \u3c 0.0011
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