4,730 research outputs found

    Usage of tracking in the CMS Level-1 trigger for the High Luminosity LHC Upgrade

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    At the High Luminosity LHC (HL-LHC), the CMS experiment will face a harsh environment with a high instantaneous luminosity up to 7x1034^{34}/cm2^2/s corresponding to an average of 140-200 multiple proton-proton collisions per bunch crossing. The main goal of the CMS Level 1 (L1) trigger upgrade for the HL-LHC is to maintain trigger thresholds that are as low as possible and comparable to those currently in use at the LHC, and to possibly include new triggers that were not feasible at the LHC. This will be achieved by upgrading the detector readout electronics, to allow a much larger L1 trigger rate, and by including, for the first time, tracking information in the L1 trigger. Examples of how this tracking information can be used to reduce the L1 trigger rates are presented.Comment: 2 pages, Contribution to the proceedings of 39th International Conference on High Energy Physics (ICHEP) in Seoul, Korea, July 4-11 201

    Top quark pair production and top quark properties at CDF

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    We present the most recent measurements of top quark pairs production and top quark properties in proton-antiproton collisions with center-of-mass energy of 1.96 TeV using CDF II detector at the Tevatron. The combination of top pair production cross section measurements and the direct measurement of top quark width are reported. The test of Standard Model predictions for top quark decaying into bb-quarks, performed by measuring the ratio RR between the top quark branching fraction to bb-quark and the branching fraction to any type of down quark is shown. The extraction of the CKM matrix element ∣Vtb∣|V_{tb}| from the ratio RR is discussed. We also present the latest measurements on the forward-backward asymmetry (AFBA_{FB}) in top anti-top quark production. With the full CDF Run II data set, the measurements are performed in top anti-top decaying to final states that contain one or two charged leptons (electrons or muons). In addition, we combine the results of the leptonic forward-backward asymmetry in ttˉt\bar t system between the two final states. All the results show deviations from the next-to-leading order (NLO) standard model (SM) calculation.Comment: 6 pages, 5 figures, Contribution to the proceedings of 37th International Conference on High Energy Physics (ICHEP) in Valencia, Spain, July 2-9 201

    Top Physics at CDF

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    We present the recent results of top-quark physics using up to 6 fb−1^{-1} of ppˉp \bar p collisions at a center of mass energy of s\sqrt s = 1.96 TeV analyzed by the CDF collaboration. Thanks to this large data sample, precision top quark measurements are now a reality at the Tevatron. Further, several new physics signals could appear in this large dataset. We will present the latest measurements of top quark intrinsic properties as well as direct searches for new physics in the top sector.Comment: Contribution to the proceedings of XIX International Workshop on Deep-Inelastic Scattering and Related Subjects (DIS 2011), 4 page

    Level-1 pixel based tracking trigger algorithm for LHC upgrade

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    The Pixel Detector is the innermost detector of the tracking system of the Compact Muon Solenoid (CMS) experiment at CERN Large Hadron Collider (LHC). It precisely determines the interaction point (primary vertex) of the events and the possible secondary vertexes due to heavy flavours (bb and cc quarks); it is part of the overall tracking system that allows reconstructing the tracks of the charged particles in the events and combined with the magnetic field to measure their impulsion. The pixel detector allows measuring the tracks in the region closest to the interaction point. The Level-1 (real-time) pixel based tracking trigger is a novel trigger system that is currently being studied for the LHC upgrade. An important goal is developing real-time track reconstruction algorithms able to cope with very high rates and high flux of data in a very harsh environment. The pixel detector has an especially crucial role in precisely identifying the primary vertex of the rare physics events from the large pile-up (PU) of events. The goal of adding the pixel information already at the real-time level of the selection is to help reducing the total level-1 trigger rate while keeping an high selection capability. This is quite an innovative and challenging objective for the experiments upgrade for the High Luminosity LHC (HL-LHC). The special case here addressed is the CMS experiment. This document describes exercises focusing on the development of a fast pixel track reconstruction where the pixel track matches with a Level-1 electron object using a ROOT-based simulation framework.Comment: Submitted to JINST; 12 pages, 10 figures, Contribution to the JINST proceedings for the INFIERI2014 School in Paris, France, July 14-25, 201

    Production of single top quark - results from the Tevatron and the LHC

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    We present the most recent measurements of single top quark production cross section by the CDF and D0 experiments at the Fermilab Tevatron Collider and the ATLAS and CMS experiments at the Large Hadron Collider (LHC). The data were collected at the Tevatron corresponding to an integrated luminosity of up to 9.7 fb−1^{-1} of proton-antiproton (ppˉp\bar p) collisions at a centre-of-mass energy of 1.96 TeV and at the LHC corresponding to an integrated luminosity of up to 4.9 fb−1^{-1} of proton-proton (pppp) collisions at a centre-of-mass energy of 7 TeV in 2011 and up to 20.3 fb−1^{-1} at a centre-of-mass energy of 8 TeV in 2012. The measurements of single top quark production in ss-channel, tt-channel and associated production of a top quark and a WW-boson (tWtW production) are presented separately and lower limits on the CKM matrix element ∣Vtb∣|V_{tb}| from the single top quark cross section are set.Comment: 5 pages, 4 figures, for the ATLAS, CDF, CMS and D0 collaborations, Presented at 26th Rencontres de Blois, Particle Physics and Cosmology, May 18-23, 201

    Contexts and Corporate Voluntary Environmental Behaviors: Examining the EPA\u27s Green Lights Voluntary Program

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    Why do an increasingly large number of firms choose to spend their own money and resources to protect the environment beyond the extant regulatory requirements? This article addresses this question by examining the EPA’s Green Lights (GL) voluntary program in which a firm’s policy makers made an early commitment to limiting greenhouse gases through the installation of energy-efficient lighting technology in its facilities. Two theoretical perspectives—resource-based theory and neo-institutional theory—are adopted to investigate the contexts by which a firm is encouraged to undertake voluntary environmental actions and evaluate environmental strategies associated with them. Accordingly, the authors focus on two major contexts: market contexts in which a firm adopts voluntary actions as a strategic response to market pressures and to advance competitiveness; and institutional contexts in which a firm takes voluntary postures as a strategic response to institutional pressures, to obtain institutional legitimacy and weaken regulatory scrutiny. The research results partially support both contexts and their associated strategic behaviors
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