834 research outputs found

    Top Physics from Run 1 and Run 2 Prospects at CDF

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    We present a summary of top quark physics results from Run 1 at CDF using the Run 1 data sample of 106 pb1^{-1}. In addition to the precursory measurements of the top quark mass and \ttbar cross section, we have performed a number of other analyses which test the consistency of the \ttbar data sample with the standard model (SM). Deviations from SM expectations could provide hints for new physics. We find that the data are consistent with the SM. While the Run 1 data are statistically limited, we have shown that the systematic uncertainties are under control and thus have layed the groundwork for higher precision tests of the SM in Run 2. This report describes the Run 1 top quark analyses and expectations and prospects for top quark measurements in Run 2.Comment: 3 page

    Upsilon Decays at CLEO

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    Using data collected using the CLEO III detector, we present recent results on decays of the Υ(1S)Υ(3S)\Upsilon(1S)-\Upsilon(3S) resonances. We report on three analyses. They are: (1) improved measurements of the muonic branching fraction of the Υ(1S)Υ(3S)\Upsilon(1S)-\Upsilon(3S), (2) precision measurements of Υ(2S)\Upsilon(2S) and Υ(3S)\Upsilon(3S) photonic transitions, and (3) new measurements of Υ(1S)\Upsilon(1S) decays to charmonium final states.}]Comment: 4 pages, 5 figures. Submitted to 32nd International Conference on High-Energy Physics (ICHEP 04), Beijing, China, 16-22 Aug 200

    Measurement of the Top Quark Mass

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    In this paper, we report on the most recent measurements of the top quark mass, performed by the CDF and D0 collaborations at the Fermilab Tevatron. The CDF collaboration has performed measurements of the top quark mass in three decay channels from which the top quark mass is measured to be 175.6 +- 6.8 GeV/c^2. The D0 collaboration combines measurements from two decay channels to obtain a top quark mass of 172.1 +- 7.1 GeV/c^2. Combining the measurements from the two experiments, assuming a 2 GeV/c^2 correlated systematic uncertainty, the measurement of the top quark mass at the Tevatron is 173.9 +- 5.2 GeV/c^2. This report presents the measurements of the top quark mass from each of the decay channels which contribute to this measurement.Comment: To be published in the 33rd proceedings of the Recontres de Moriond, Les Arcs, France, March 21-28, 1998. 6 pages, 3 figure

    Testbeam studies of pre-prototype silicon strip sensors for the LHCb UT upgrade project

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    The LHCb experiment is preparing for a major upgrade in 2018-2019. One of the key components in the upgrade is a new silicon tracker situated upstream of the analysis magnet of the experiment. The Upstream Tracker (UT) will consist of four planes of silicon strip detectors, with each plane covering an area of about 2 m2^2. An important consideration of these detectors is their performance after they have been exposed to a large radiation dose. In this article we present test beam results of pre-prototype n-in-p and p-in-n sensors that have been irradiated with fluences up to 4.0×10144.0\times10^{14} neqn_{\rm eq} cm2^{-2}.Comment: 25 pages, 20 figure

    The Long-Baseline Neutrino Experiment: Exploring Fundamental Symmetries of the Universe

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    The preponderance of matter over antimatter in the early Universe, the dynamics of the supernova bursts that produced the heavy elements necessary for life and whether protons eventually decay --- these mysteries at the forefront of particle physics and astrophysics are key to understanding the early evolution of our Universe, its current state and its eventual fate. The Long-Baseline Neutrino Experiment (LBNE) represents an extensively developed plan for a world-class experiment dedicated to addressing these questions. LBNE is conceived around three central components: (1) a new, high-intensity neutrino source generated from a megawatt-class proton accelerator at Fermi National Accelerator Laboratory, (2) a near neutrino detector just downstream of the source, and (3) a massive liquid argon time-projection chamber deployed as a far detector deep underground at the Sanford Underground Research Facility. This facility, located at the site of the former Homestake Mine in Lead, South Dakota, is approximately 1,300 km from the neutrino source at Fermilab -- a distance (baseline) that delivers optimal sensitivity to neutrino charge-parity symmetry violation and mass ordering effects. This ambitious yet cost-effective design incorporates scalability and flexibility and can accommodate a variety of upgrades and contributions. With its exceptional combination of experimental configuration, technical capabilities, and potential for transformative discoveries, LBNE promises to be a vital facility for the field of particle physics worldwide, providing physicists from around the globe with opportunities to collaborate in a twenty to thirty year program of exciting science. In this document we provide a comprehensive overview of LBNE's scientific objectives, its place in the landscape of neutrino physics worldwide, the technologies it will incorporate and the capabilities it will possess.Comment: Major update of previous version. This is the reference document for LBNE science program and current status. Chapters 1, 3, and 9 provide a comprehensive overview of LBNE's scientific objectives, its place in the landscape of neutrino physics worldwide, the technologies it will incorporate and the capabilities it will possess. 288 pages, 116 figure

    Les droits disciplinaires des fonctions publiques : « unification », « harmonisation » ou « distanciation ». A propos de la loi du 26 avril 2016 relative à la déontologie et aux droits et obligations des fonctionnaires

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    The production of tt‾ , W+bb‾ and W+cc‾ is studied in the forward region of proton–proton collisions collected at a centre-of-mass energy of 8 TeV by the LHCb experiment, corresponding to an integrated luminosity of 1.98±0.02 fb−1 . The W bosons are reconstructed in the decays W→ℓν , where ℓ denotes muon or electron, while the b and c quarks are reconstructed as jets. All measured cross-sections are in agreement with next-to-leading-order Standard Model predictions.The production of ttt\overline{t}, W+bbW+b\overline{b} and W+ccW+c\overline{c} is studied in the forward region of proton-proton collisions collected at a centre-of-mass energy of 8 TeV by the LHCb experiment, corresponding to an integrated luminosity of 1.98 ±\pm 0.02 \mbox{fb}^{-1}. The WW bosons are reconstructed in the decays WνW\rightarrow\ell\nu, where \ell denotes muon or electron, while the bb and cc quarks are reconstructed as jets. All measured cross-sections are in agreement with next-to-leading-order Standard Model predictions

    Physics case for an LHCb Upgrade II - Opportunities in flavour physics, and beyond, in the HL-LHC era

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    The LHCb Upgrade II will fully exploit the flavour-physics opportunities of the HL-LHC, and study additional physics topics that take advantage of the forward acceptance of the LHCb spectrometer. The LHCb Upgrade I will begin operation in 2020. Consolidation will occur, and modest enhancements of the Upgrade I detector will be installed, in Long Shutdown 3 of the LHC (2025) and these are discussed here. The main Upgrade II detector will be installed in long shutdown 4 of the LHC (2030) and will build on the strengths of the current LHCb experiment and the Upgrade I. It will operate at a luminosity up to 2×1034 cm−2s−1, ten times that of the Upgrade I detector. New detector components will improve the intrinsic performance of the experiment in certain key areas. An Expression Of Interest proposing Upgrade II was submitted in February 2017. The physics case for the Upgrade II is presented here in more depth. CP-violating phases will be measured with precisions unattainable at any other envisaged facility. The experiment will probe b → sl+l−and b → dl+l− transitions in both muon and electron decays in modes not accessible at Upgrade I. Minimal flavour violation will be tested with a precision measurement of the ratio of B(B0 → μ+μ−)/B(Bs → μ+μ−). Probing charm CP violation at the 10−5 level may result in its long sought discovery. Major advances in hadron spectroscopy will be possible, which will be powerful probes of low energy QCD. Upgrade II potentially will have the highest sensitivity of all the LHC experiments on the Higgs to charm-quark couplings. Generically, the new physics mass scale probed, for fixed couplings, will almost double compared with the pre-HL-LHC era; this extended reach for flavour physics is similar to that which would be achieved by the HE-LHC proposal for the energy frontier
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