2,192 research outputs found

    Combined search for the quarks of a sequential fourth generation

    Get PDF
    Results are presented from a search for a fourth generation of quarks produced singly or in pairs in a data set corresponding to an integrated luminosity of 5 inverse femtobarns recorded by the CMS experiment at the LHC in 2011. A novel strategy has been developed for a combined search for quarks of the up and down type in decay channels with at least one isolated muon or electron. Limits on the mass of the fourth-generation quarks and the relevant Cabibbo-Kobayashi-Maskawa matrix elements are derived in the context of a simple extension of the standard model with a sequential fourth generation of fermions. The existence of mass-degenerate fourth-generation quarks with masses below 685 GeV is excluded at 95% confidence level for minimal off-diagonal mixing between the third- and the fourth-generation quarks. With a mass difference of 25 GeV between the quark masses, the obtained limit on the masses of the fourth-generation quarks shifts by about +/- 20 GeV. These results significantly reduce the allowed parameter space for a fourth generation of fermions.Comment: Replaced with published version. Added journal reference and DO

    Numerical assessment of integrated thermal management systems in electrified powertrains

    Get PDF
    Temperatures in internal combustion engines (ICE) impact fuel consumption and pollutant emissions, especially under transient operating conditions. In hybrid powertrains, where the reciprocating internal combustion engine has intermittent operating conditions, a optimum control of these temperatures is critical. In this work, a detailed methodology for studying integrated thermal management systems for hybrid propulsion system was presented. Both experimental measurements and 0D/1D models were implemented and validated for the different components of the hybrid vehicle powertrain. The novelty of this work consists in the extensive experimental measurements involved for the development of the different models, specially the ICE, in order to study the integration of the different thermal flows of a hybrid powertrain. Furthermore, the simulation methodology used in this work integrates different modelling tools and takes advantage of their strengths when compared to using a single modelling tool. Two different thermal management systems have been evaluated under different Real Driving Emission (RDE) cycles at two different temperatures (at 20 °C and -20 °C). Results have shown that during the ICE warming up, the integrated thermal management system improved energy consumption by 1.74% and 3% for warm and cold conditions, respectively. This was because, the integrated TMS allows to avoid the temperature drop of the ICE when the propulsive system is in pure electric mode. © 2022 Elsevier Lt

    Search for heavy gauge W ' bosons in events with an energetic lepton and large missing transverse momentum at root s=13TeV

    Get PDF
    Peer reviewe

    Search for massive resonances decaying in to WW,WZ or ZZ bosons in proton-proton collisions at root s=13 TeV

    Get PDF
    Peer reviewe

    Search for narrow resonances in dilepton mass spectra in proton-proton collisions at sqrt(s) = 13 TeV and combination with 8 TeV data

    Get PDF
    A search for narrow resonances in dielectron and dimuon invariant mass spectra has been performed using data obtained from proton–proton collisions at View the MathML sources=13 TeV collected with the CMS detector. The integrated luminosity for the dielectron sample is 2.7 fb−1 and for the dimuon sample 2.9 fb−1. The sensitivity of the search is increased by combining these data with a previously analyzed set of data obtained at View the MathML sources=8 TeV and corresponding to a luminosity of 20 fb−1. No evidence for non-standard-model physics is found, either in the 13 TeV data set alone, or in the combined data set. Upper limits on the product of production cross section and branching fraction have also been calculated in a model-independent manner to enable interpretation in models predicting a narrow dielectron or dimuon resonance structure. Limits are set on the masses of hypothetical particles that could appear in new-physics scenarios. For the View the MathML sourceZSSM′ particle, which arises in the sequential standard model, and for the superstring inspired View the MathML sourceZψ′ particle, 95% confidence level lower mass limits for the combined data sets and combined channels are found to be 3.37 and 2.82 TeV, respectively. The corresponding limits for the lightest Kaluza–Klein graviton arising in the Randall–Sundrum model of extra dimensions with coupling parameters 0.01 and 0.10 are 1.46 and 3.11 TeV, respectively. These results significantly exceed the limits based on the 8 TeV LHC data

    Search for Pair Production of Third-Generation Leptoquarks and Top Squarks in pp Collisions at √s=7  TeV

    Get PDF
    Results are presented from a search for the pair production of third-generation scalar and vector leptoquarks, as well as for top squarks in R-parity-violating supersymmetric models. In either scenario, the new, heavy particle decays into a τ lepton and a b quark. The search is based on a data sample of pp collisions at √s=7  TeV, which is collected by the CMS detector at the LHC and corresponds to an integrated luminosity of 4.8  fb[superscript -1]. The number of observed events is found to be in agreement with the standard model prediction, and exclusion limits on mass parameters are obtained at the 95% confidence level. Vector leptoquarks with masses below 760 GeV are excluded and, if the branching fraction of the scalar leptoquark decay to a τ lepton and a b quark is assumed to be unity, third-generation scalar leptoquarks with masses below 525 GeV are ruled out. Top squarks with masses below 453 GeV are excluded for a typical benchmark scenario, and limits on the coupling between the top squark, τ lepton, and b quark, λ333′ are obtained. These results are the most stringent for these scenarios to date

    Measurement of top quark–antiquark pair production in association with a W or Z boson in pp collisions at √s=8 TeV

    Get PDF
    Peer reviewe

    Observation of the diphoton decay of the Higgs boson and measurement of its properties

    Get PDF
    Peer reviewe

    Search for light bosons in decays of the 125 GeV Higgs boson in proton-proton collisions at root s=8 TeV

    Get PDF
    Peer reviewe

    Search for the production of dark matter in association with top-quark pairs in the single-lepton final state in proton-proton collisions at √s=8 TeV

    Get PDF
    Peer reviewe
    corecore