246 research outputs found

    Evidence for the 125 GeV Higgs boson decaying to a pair of tau leptons

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    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

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    Search for vector-like T quarks decaying to top quarks and Higgs bosons in the all-hadronic channel using jet substructure

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    Replacing Conventional Carbon Nucleophiles with Electrophiles: Nickel-Catalyzed Reductive Alkylation of Aryl Bromides and Chlorides

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    Description and performance of track and primary-vertex reconstruction with the CMS tracker

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    A description is provided of the software algorithms developed for the CMS tracker both for reconstructing charged-particle trajectories in proton-proton interactions and for using the resulting tracks to estimate the positions of the LHC luminous region and individual primary-interaction vertices. Despite the very hostile environment at the LHC, the performance obtained with these algorithms is found to be excellent. For tbar t events under typical 2011 pileup conditions, the average track-reconstruction efficiency for promptly-produced charged particles with transverse momenta of pT > 0.9GeV is 94% for pseudorapidities of |η| < 0.9 and 85% for 0.9 < |η| < 2.5. The inefficiency is caused mainly by hadrons that undergo nuclear interactions in the tracker material. For isolated muons, the corresponding efficiencies are essentially 100%. For isolated muons of pT = 100GeV emitted at |η| < 1.4, the resolutions are approximately 2.8% in pT, and respectively, 10μm and 30μm in the transverse and longitudinal impact parameters. The position resolution achieved for reconstructed primary vertices that correspond to interesting pp collisions is 10–12μm in each of the three spatial dimensions. The tracking and vertexing software is fast and flexible, and easily adaptable to other functions, such as fast tracking for the trigger, or dedicated tracking for electrons that takes into account bremsstrahlung

    Measurement of inclusive jet production and nuclear modifications in pPb collisions at root s(NN)=5.02 TeV

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    Measurements of the tt¯ charge asymmetry using the dilepton decay channel in pp collisions at √s=7 TeV

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    Evidence for the 125 GeV Higgs boson decaying to a pair of tau leptons

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    A search for a standard model Higgs boson decaying into a pair of &#964; leptons is performed using events recorded by the CMS experiment at the LHC in 2011 and 2012. The dataset corresponds to an integrated luminosity of 4.9 fb &#8722;1 at a centre-of-mass energy of 7 TeV and 19.7 fb &#8722;1 at 8 TeV. Each &#964; lepton decays hadronically or leptonically to an electron or a muon, leading to six different final states for the &#964; -lepton pair, all considered in this analysis. An excess of events is observed over the expected background contributions, with a local significance larger than 3 standard deviations for m H values between 115 and 130 GeV. The best fit of the observed H &#8594; &#964; &#964; signal cross section times branching fraction for m H = 125 GeV is 0 . 78 ± 0 . 27 times the standard model expectation. These observations constitute evidence for the 125 GeV Higgs boson decaying to a pair of &#964; leptons

    Observation of top quark pairs produced in association with a vector boson in pp collisions at s=8 √s=8TeV

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    Measurements of the cross sections for top quark pairs produced in association with a W or Z boson are presented, using 8 TeV pp collision data corresponding to an integrated luminosity of 19.5 fb −1 , collected by the CMS experiment at the LHC. Final states are selected in which the associated W boson decays to a charged lepton and a neutrino or the Z boson decays to two charged leptons. Signal events are identified by matching reconstructed objects in the detector to specific final state particles from t t ¯ W tt¯W or t t ¯ Z tt¯Z decays. The t t ¯ W tt¯W cross section is measured to be 382 − 102 + 117 fb with a significance of 4.8 standard deviations from the background-only hypothesis. The t t ¯ Z tt¯Z cross section is measured to be 242 − 55 + 65 fb with a significance of 6.4 standard deviations from the background-only hypothesis. These measurements are used to set bounds on five anomalous dimension-six operators that would affect the t t ¯ W tt¯W and t t ¯ Z tt¯Z cross sections

    Search for supersymmetry in events with a photon, a lepton, and missing transverse momentum in pp collisions at root s=8 TeV

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