4,359 research outputs found

    Top Quark Mass Measurements at the Tevatron

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    The general strategy, as well as channel-specific details, applied to the measurement of the top quark mass at the Tevatron in Run I are reviewed, and the combination of the results obtained by the CDF and DO collaborations presented. The accelerator and detector upgrades for Run II are described, and expected improvements in the systematic uncertainties on the measurement evaluated.Comment: Latex (Frascati.sty), 11 pages, 3 figs. Talk given at the 14th Rencontres de Physique de la Vallee d'Aoste, La Thuile, Aosta Valley, Italy, February 200

    Searches for New Physics at D0

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    The integrated luminosity at Run 2 of the Tevatron is approaching the Run 1 total, and data analysis is progressing. New results in searches for new physics by the DO experiment are presented in a variety of channels, demonstrating good performance of the detector and detailed understanding of the data.Comment: 6 pages, proceedings of the 38th Rencontres de Morion

    Mixing and CP Violation at the Tevatron

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    Measurements of meson mixing and CP violation parameters obtained by the CDF and D0 experiments at the Fermilab Tevatron are presented. These include results on BsB_s and DD meson mixing, and searches for CP violation in the decay B+→J/ψK+B^+ \to J/\psi K^+, in mixing through semileptonic BsB_s meson decays, and in the interference between mixing and decay in the process Bs→J/ψϕB_s \to J/\psi \phi.Comment: 9 pages, Proceedings of the Hadron Collider Physics Symposium (HCP2008),Galena, Illinois, US

    Determination of Scanning Efficiencies in Experiments Using Nuclear Emulsion Sheets

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    During their exposure, nuclear emulsion sheets detect both tracks from experiment-related particles, as well as a considerable amount of background tracks, mainly due to cosmic rays. Unless the exposure has been fairly short, it is therefore fairly likely that a fraction of the tracks that have been identified as belonging to the particles the experiment is interested in, are really due to background. A method, which allows to measure this fraction reliably directly from the data, is described.Comment: 7 pages, uses elsart, to be published in NIMA 450, p 44

    ATLAS Upgrade Instrumentation in the US

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    Planned upgrades of the LHC over the next decade should allow the machine to operate at a center of mass energy of 14 TeV with instantaneous luminosities in the range 5--7e34 cm^-2 s^-1. With these parameters, ATLAS could collect 3,000 fb^-1 of data in approximately 10 years. However, the conditions under which this data would be acquired are much harsher than those currently encountered at the LHC. For example, the number of proton-proton interactions per bunch crossing will rise from the level of 20--30 per 50 ns crossing observed in 2012 to 140--200 every 25 ns. In order to deepen our understanding of the newly discovered Higgs boson and to extend our searches for physics beyond that new particle, the ATLAS detector, trigger, and readout will have to undergo significant upgrades. In this whitepaper we describe R&D necessary for ATLAS to continue to run effectively at the highest luminosities foreseen from the LHC. Emphasis is placed on those R&D efforts in which US institutions are playing a leading role.Comment: Snowmass contributed paper, 24 pages, 12 figure

    A Radiation-Hard Dual Channel 4-bit Pipeline for a 12-bit 40 MS/s ADC Prototype with extended Dynamic Range for the ATLAS Liquid Argon Calorimeter Readout Electronics Upgrade at the CERN LHC

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    The design of a radiation-hard dual channel 12-bit 40 MS/s pipeline ADC with extended dynamic range is presented, for use in the readout electronics upgrade for the ATLAS Liquid Argon Calorimeters at the CERN Large Hadron Collider. The design consists of two pipeline A/D channels with four Multiplying Digital-to-Analog Converters with nominal 12-bit resolution each. The design, fabricated in the IBM 130 nm CMOS process, shows a performance of 68 dB SNDR at 18 MHz for a single channel at 40 MS/s while consuming 55 mW/channel from a 2.5 V supply, and exhibits no performance degradation after irradiation. Various gain selection algorithms to achieve the extended dynamic range are implemented and tested.Comment: 22 pages, 22 figures, accepted by JINS

    High pT Hadronic Top Quark Identification

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    At the LHC objects with masses at the electroweak scale will for the first time be produced with very large transverse momenta. In many cases, these objects decay hadronically, producing a set of collimated jets. This interesting new experimental phenomenology requires the development and tuning of new tools, since the usual reconstruction methods would simply reconstruct a single jet. This note describes the application of the YSplitter algorithm in conjunction with the jet mass to identify high transverse momentum top quarks decaying hadronically

    A Supersymmetric Solution to the Solar and Atmospheric Neutrino Anomalies

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    The formalism for neutrino flavor change induced by lepton family number violating interactions is developed for the three-neutrino case, and used to derive the corresponding flavor change probabilities in matter. Applied to the solar and atmospheric neutrino fluxes, it is argued that the observed anomalies, including the zenith dependence for the atmospheric case, could be due to such interactions.Comment: 6 pages, 1 figure Modifications: include limit from tau -> rho mu (leads to somewhat different conclusions) and a change to the figur
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