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Measurement of the top-quark mass in tt − events with lepton+jets final states in pp collisions at √s =7 TeV
(2012)Journal of High Energy PhysicsThe mass of the top quark is measured using a sample of tt¯ candidate events with one electron or muon and at least four jets in the final state, collected by CMS in pp collisions at s√=7 TeV at the LHC. A total of 5174 candidate events is selected from data corresponding to an integrated luminosity of 5.0 fb−1. For each event the mass is reconstructed from a kinematic fit of the decay products to a tt¯ hypothesis. The top-quark mass is ...Journal Article -
Observation of Sequential gamma Suppression in PbPb Collisions
(2012)Physical Review LettersThe suppression of the individual Υ(nS) states in PbPb collisions with respect to their yields in pp data has been measured. The PbPb and pp data sets used in the analysis correspond to integrated luminosities of 150 μb−1 and 230 nb−1, respectively, collected in 2011 by the CMS experiment at the LHC, at a center-of-mass energy per nucleon pair of 2.76 TeV. The Υ(nS) yields are measured from the dimuon invariant mass spectra. The suppression ...Journal Article -
A search for a doubly-charged Higgs boson in pp collisions at √s=7 TeV
(2012)The European Physical Journal CA search for a doubly-charged Higgs boson in pp collisions at s√=7 TeV is presented. The data correspond to an integrated luminosity of 4.9 fb−1, collected by the CMS experiment at the LHC. The search is performed using events with three or more isolated charged leptons of any flavor, giving sensitivity to the decays of pair-produced triplet components Φ ++ Φ −−, and Φ ++ Φ − from associated production. No excess is observed compared to ...Journal Article -
Ratios of dijet production cross sections as a function of the absolute difference in rapidity between jets in proton–proton collisions at √s=7 TeV
(2012)The European Physical Journal CA study of dijet production in proton–proton collisions was performed at s√=7~TeV for jets with p T>35 GeV and |y|<4.7 using data collected with the CMS detector at the LHC in 2010. Events with at least one pair of jets are denoted as “inclusive”. Events with exactly one pair of jets are called “exclusive”. The ratio of the cross section of all pairwise combinations of jets to the exclusive dijet cross section as a function of the rapidity ...Journal Article -
Measurement of the tt¯ production cross section in the dilepton channel in pp collisions at √s=7 TeV
(2012)Journal of High Energy PhysicsThe tt¯ production cross section (σtt¯) is measured in proton-proton collisions at s√=7 TeV in data collected by the CMS experiment, corresponding to an integrated luminosity of 2.3 fb−1. The measurement is performed in events with two leptons (electrons or muons) in the final state, at least two jets identified as jets originating from b quarks, and the presence of an imbalance in transverse momentum. The measured value of σtt¯ for a ...Journal Article -
Search for exclusive or semi-exclusive photon pair production and observation of exclusive and semi-exclusive electron pair production in pp collisions at √s=7 TeV
(2012)Journal of High Energy PhysicsA search for exclusive or semi-exclusive γγ production, pp → p(*) + γγ + p(*) (where p* stands for a diffractively-dissociated proton), and the observation of exclusive and semi-exclusive e+e− production, pp → p(*) + e+e− + p(*), in proton-proton collisions at s√=7 TeV, are presented. The analysis is based on a data sample corresponding to an integrated luminosity of 36 pb−1 recorded by the CMS experiment at the LHC at low instantaneous ...Journal Article -
Search for electroweak production of charginos and neutralinos using leptonic final states in pp collisions at √s=7 TeV
(2012)Journal of High Energy PhysicsThe 2011 dataset of the CMS experiment, consisting of an integrated luminosity of 4.98 fb−1 of pp collisions at s√=7 TeV, enables expanded searches for direct electroweak pair production of charginos and neutralinos in supersymmetric models as well as their analogs in other models of new physics. Searches sensitive to such processes, with decays to final states that contain two or more leptons, are presented. Final states with three ...Journal Article -
Search for new physics with long-lived particles decaying to photons and missing energy in pp collisions at √s=7 TeV
(2012)Journal of High Energy PhysicsA search is performed for long-lived neutral particles decaying into a photon and invisible particles. An example of such a signature is the decay of the lightest neutralino with nonzero lifetime into a gravitino and a photon in gauge-mediated supersymmetry, with the neutralino as the next-to-lightest supersymmetric particle and the gravitino as the lightest. The search uses events containing photons, missing transverse energy, and jets. ...Journal Article -
Search for charge-asymmetric production of W′ bosons in top pair + jet events from pp collisions at √s = 7 TeV
(2012)Physics Letters BA search is presented for charge-asymmetric production of a W' boson that has been proposed to accommodate the forward-backward asymmetry observed in the production of top-antitop quark pairs at the Tevatron. The new heavy W' boson would be produced in association with a top quark and would decay into top and down quarks. The data correspond to an integrated luminosity of 5.0 fb(-1) in pp collisions at a center-of-mass energy of 7 TeV, ...Journal Article -
Study of the inclusive production of charged pions, kaons, and protons in pp collisions at √s=0.9, 2.76, and 7 TeV
(2012)The European Physical Journal CSpectra of identified charged hadrons are measured in pp collisions at the LHC for s√=0.9,2.76, and 7 TeV. Charged pions, kaons, and protons in the transverse-momentum range p T≈0.1–1.7 GeV/c and for rapidities |y|<1 are identified via their energy loss in the CMS silicon tracker. The average p T increases rapidly with the mass of the hadron and the event charged-particle multiplicity, independently of the center-of-mass energy. The fully ...Journal Article