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Description and performance of track and primary-vertex reconstruction with the CMS tracker akahashi
(2014)Journal of InstrumentationA 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 ...Journal Article -
Measurement of the ratio of inclusive jet cross sections using the anti-kT algorithm with radius parameters R=0.5 and 0.7 in pp collisions at √s=7 TeV
(2014)Physical Review DMeasurements of the inclusive jet cross section with the anti-kT clustering algorithm are presented for two radius parameters, R=0.5 and 0.7. They are based on data from LHC proton-proton collisions at √s=7 TeV corresponding to an integrated luminosity of 5.0 fb−1 collected with the CMS detector in 2011. The ratio of these two measurements is obtained as a function of the rapidity and transverse momentum of the jets. Significant ...Journal Article -
Evidence of b -Jet Quenching in PbPb Collisions at √sNN =2.76 TeV
(2014)Physical Review LettersThe production of jets associated to bottom quarks is measured for the first time in PbPb collisions at a center-of-mass energy of 2.76 TeV per nucleon pair. Jet spectra are reported in the transverse momentum (pT) range of 80-250GeV/c, and within pseudorapidity |η|<2. The nuclear modification factor (RAA) calculated from these spectra shows a strong suppression in the b-jet yield in PbPb collisions relative to the yield observed in pp ...Journal Article -
Measurement of jet fragmentation in PbPb and pp collisions at √sNN = 2.76 TeV
(2014)Physical Review CThe jet fragmentation function of inclusive jets with transverse momentum pT above 100GeV/c in PbPb collisions has been measured using reconstructed charged particles with pT above 1GeV/c in a cone of radius 0.3 around the jet axis. A data sample of PbPb collisions collected in 2011 at a nucleon-nucleon center-of-mass energy of √sNN=2.76TeV corresponding to an integrated luminosity of 150μb−1 is used. The results for PbPb collisions as a ...Journal Article -
Search for supersymmetry in pp collisions at √s= 8 TeV in events with a single lepton, large jet multiplicity, and multiple b jets
(2014)Physics Letters BResults are reported from a search for supersymmetry in pp collisions at a center-of-mass energy of 8 TeV, based on events with a single isolated lepton (electron or muon) and multiple jets, at least two of which are identified as b jets. The data sample corresponds to an integrated luminosity of 19.3 fb(-1) recorded by the CMS experiment at the LHC in 2012. The search is motivated by supersymmetric models that involve strong-production ...Journal Article -
Observation of the associated production of a single top quark and a W Boson in pp collisions at √s = 8 TeV
(2014)Physical Review LettersJournal Article -
Alignment of the CMS tracker with LHC and cosmic ray data
(2014)Journal of InstrumentationThe central component of the CMS detector is the largest silicon tracker ever built. The precise alignment of this complex device is a formidable challenge, and only achievable with a significant extension of the technologies routinely used for tracking detectors in the past. This article describes the full-scale alignment procedure as it is used during LHC operations. Among the specific features of the method are the simultaneous ...Journal Article -
Measurement of Inclusive W and Z Boson Production Cross Sections in pp Collisions at √s =8 Te V
(2014)Physical Review LettersA measurement of total and fiducial inclusive W and Z boson production cross sections in pp collisions at √s=8 TeV is presented. Electron and muon final states are analyzed in a data sample collected with the CMS detector corresponding to an integrated luminosity of 18.2±0.5 pb−1. The measured total inclusive cross sections times branching fractions are σ(pp→WX)×B(W→ℓν)=12.21±0.03(stat)±0.24(syst)±0.32(lum) nb and σ(pp→ZX)×B(Z→ℓ+ℓ−)= ...Journal Article -
Measurement of the properties of a Higgs boson in the four-lepton final state
(2014)Physical Review DThe properties of a Higgs boson candidate are measured in the H→ZZ→4ℓ decay channel, with ℓ=e, μ, using data from pp collisions corresponding to an integrated luminosity of 5.1 fb−1 at the center-of-mass energy of √s=7 TeV and 19.7 fb−1 at √s=8 TeV, recorded with the CMS detector at the LHC. The new boson is observed as a narrow resonance with a local significance of 6.8 standard deviations, a measured mass of 125.6±0.4(stat)±0.2(syst) GeV, ...Journal Article -
Search for Flavor-Changing Neutral Currents in Top-Quark Decays t→Zq in pp Collisions at √s = 8 TeV
(2014)Physical Review LettersA search for flavor-changing neutral currents in top-quark decays t → Zq is performed in events produced from the decay chain t¯t → Zq + Wb, where both vector bosons decay leptonically, producing a final state with three leptons (electrons or muons). A data set collected with the CMS detector at the LHC is used, corresponding to an integrated luminosity of 19.7 fb−1 of proton-proton collisions at a center-of-mass energy of 8 TeV. No excess ...Journal Article