107 research outputs found

    Measurement of the mass difference between top quark and antiquark in pp collisions at root s=8 TeV

    Get PDF
    Peer reviewe

    Measurement of nuclear modification factors of ΄(1S), ΄(2S), and ΄(3S) mesons in PbPb collisions at √sNN = 5.02 TeV

    Get PDF

    Search for gauge-mediated supersymmetry in events with at least one photon and missing transverse momentum in pp collisions at √s = 13 TeV

    Get PDF
    A search for gauge-mediated supersymmetry (SUSY) in final states with photons and large missing transverse momentum is presented. The data sample of pp collisions at s=13TeV was collected with the CMS detector at the CERN LHC and corresponds to an integrated luminosity of 35.9 fb−1. Data are compared with models in which the lightest neutralino has bino- or wino-like components, resulting in decays to photons and gravitinos, where the gravitinos escape detection. The event selection is optimized for both electroweak (EWK) and strong production SUSY scenarios. The observed data are consistent with standard model predictions, and limits are set in the context of a general gauge mediation model in which gaugino masses up to 980 GeV are excluded at 95% confidence level. Gaugino masses below 780 and 950 GeV are excluded in two simplified models with EWK production of mass-degenerate charginos and neutralinos. Stringent limits are set on simplified models based on gluino and squark pair production, excluding gluino (squark) masses up to 2100 (1750) GeV depending on the assumptions made for the decay modes and intermediate particle masses. This analysis sets the highest mass limits to date in the studied EWK models, and in the considered strong production models when the mass difference between the gauginos and the squarks or gluinos is small

    Performance of reconstruction and identification of τ leptons decaying to hadrons and vτ in pp collisions at √s=13 TeV

    Get PDF
    The algorithm developed by the CMS Collaboration to reconstruct and identify τ leptons produced in proton-proton collisions at √s=7 and 8 TeV, via their decays to hadrons and a neutrino, has been significantly improved. The changes include a revised reconstruction of π⁰ candidates, and improvements in multivariate discriminants to separate τ leptons from jets and electrons. The algorithm is extended to reconstruct τ leptons in highly Lorentz-boosted pair production, and in the high-level trigger. The performance of the algorithm is studied using proton-proton collisions recorded during 2016 at √s=13 TeV, corresponding to an integrated luminosity of 35.9 fbÂŻÂč. The performance is evaluated in terms of the efficiency for a genuine τ lepton to pass the identification criteria and of the probabilities for jets, electrons, and muons to be misidentified as τ leptons. The results are found to be very close to those expected from Monte Carlo simulation

    Search for excited quarks of light and heavy flavor in γ  + jet final states in proton–proton collisions at √s = 13 TeV

    Get PDF
    A search is presented for excited quarks of light and heavy flavor that decay to Îł+jet final states. The analysis is based on data corresponding to an integrated luminosity of 35.9 fb⁻Âč collected by the CMS experiment in proton–proton collisions at √s=13TeV at the LHC. A signal would appear as a resonant contribution to the invariant mass spectrum of the Îł+jet system, above the background expected from standard model processes. No resonant excess is found, and upper limits are set on the product of the excited quark cross section and its branching fraction as a function of its mass. These are the most stringent limits to date in the Îł+jet final state, and exclude excited light quarks with masses below 5.5 TeV and excited b quarks with masses below 1.8 TeV, assuming standard model like coupling strengths

    Search for the associated production of the Higgs boson with a top-quark pair

    Get PDF
    A search for the standard model Higgs boson produced in association with a top-quark pair t t ÂŻ H (ttÂŻH) is presented, using data samples corresponding to integrated luminosities of up to 5.1 fb −1 and 19.7 fb −1 collected in pp collisions at center-of-mass energies of 7 TeV and 8 TeV respectively. The search is based on the following signatures of the Higgs boson decay: H → hadrons, H → photons, and H → leptons. The results are characterized by an observed t t ÂŻ H ttÂŻH signal strength relative to the standard model cross section, μ = σ/σ SM ,under the assumption that the Higgs boson decays as expected in the standard model. The best fit value is μ = 2.8 ± 1.0 for a Higgs boson mass of 125.6 GeV

    Observation of nuclear modifications in W±^{±} boson production in pPb collisions at √S^{S}NN = 8.16 TeV

    Get PDF

    Identification techniques for highly boosted W bosons that decay into hadrons

    Get PDF

    Measurement of the production cross section for a W boson and two b jets in pp collisions at root s=7 TeV

    Get PDF
    The production cross section for a W boson and two b jets is measured using proton&#8211;proton collisions at s=7 TeV in a data sample collected with the CMS experiment at the LHC corresponding to an integrated luminosity of 5.0 fb &#8722;1 . The W+bbÂŻ events are selected in the W&#8594;&#956;&#957; decay mode by requiring a muon with transverse momentum pT>25 GeV and pseudorapidity |&#951;|25 GeV and |&#951;|<2.4 . The measured W+bbÂŻ production cross section in the fiducial region, calculated at the level of final-state particles, is &#963;(pp&#8594;W+bbÂŻ)×B(W&#8594;&#956;&#957;)=0.53±0.05(stat.)±0.09(syst.)±0.06(theo.)±0.01(lum.) pb , in agreement with the standard model prediction. In addition, kinematic distributions of the W+bbÂŻ system are in agreement with the predictions of a simulation using MadGraph and pythia

    Measurement of prompt ψ(2S) production cross sections in proton–lead and proton–proton collisions at √SNN = 5.02 TeV

    Get PDF
    • 

    corecore