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Measurement of the tt ¯ production cross section in the dilepton channel in pp collisions at root s=8 TeV
(2014)Journal of High Energy PhysicsThe top-antitop quark (tt¯) production cross section is measured in proton-proton collisions at s√ = 8 TeV with the CMS experiment at the LHC, using a data sample corresponding to an integrated luminosity of 5.3 fb−1. The measurement is performed by analysing events with a pair of electrons or muons, or one electron and one muon, and at least two jets, one of which is identified as originating from hadronisation of a bottom quark. The ...Journal Article -
Observation of the diphoton decay of the Higgs boson and measurement of its properties
(2014)The European Physical Journal CObservation of the diphoton decay mode of the recently discovered Higgs boson and measurement of some of its properties are reported. The analysis uses the entire dataset collected by the CMS experiment in proton-proton collisions during the 2011 and 2012 LHC running periods. The data samples correspond to integrated luminosities of 5.1fb-1at s√=7TeV and 19.7fb-1at 8TeV . A clear signal is observed in the diphoton channel at a mass close ...Journal Article -
Study of hadronic event-shape variables in multijet final states in pp collisions at √s = 7 TeV
(2014)Journal of High Energy PhysicsEvent-shape variables, which are sensitive to perturbative and nonperturbative aspects of quantum chromodynamic (QCD) interactions, are studied in multijet events recorded in proton-proton collisions at s√=7 TeV. Events are selected with at least one jet with transverse momentum p T > 110 GeV and pseudorapidity |η| < 2.4, in a data sample corresponding to integrated luminosities of up to 5 fb−1. The distributions of five event-shape ...Journal Article -
Study of double parton scattering using W + 2-jet events in proton-proton collisions at √s = 7 TeV
(2014)Journal of High Energy PhysicsDouble parton scattering is investigated in proton-proton collisions at s√ = 7 TeV where the final state includes a W boson, which decays into a muon and a neutrino, and two jets. The data sample corresponds to an integrated luminosity of 5 fb−1, collected with the CMS detector at the LHC. Observables sensitive to double parton scattering are investigated after being corrected for detector effects and selection efficiencies. The fraction ...Journal Article -
Search for massive resonances in dijet systems containing jets tagged as W or Z boson decays in pp collisions at √s = 8 TeV
(2014)Journal of High Energy PhysicsA search is reported for massive resonances decaying into a quark and a vector boson (W or Z), or two vector bosons (WW, WZ, or ZZ). The analysis is performed on an inclusive sample of multijet events corresponding to an integrated luminosity of 19.7 fb−1, collected in proton-proton collisions at a centre-of-mass energy of 8 TeV with the CMS detector at the LHC. The search uses novel jet-substructure identification techniques that provide ...Journal 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 -
Search for Top Squark and Higgsino Production Using Diphoton Higgs Boson Decays
(2014)Physical Review LettersResults are presented of a search for a “natural” supersymmetry scenario with gauge mediated symmetry breaking. It is assumed that only the supersymmetric partners of the top quark (the top squark) and the Higgs boson (Higgsino) are accessible. Events are examined in which there are two photons forming a Higgs boson candidate, and at least two b-quark jets. In 19.7 fb−1 of proton-proton collision data at s=8 TeV, recorded in the CMS ...Journal Article -
Measurement of the production cross sections for a Z boson and one or more b jets in pp collisions at sqrt(s) = 7 TeV
(2014)Journal of High Energy PhysicsThe production of a Z boson, decaying into two leptons and produced in association with one or more b jets, is studied using proton-proton collisions delivered by the LHC at a centre-of-mass energy of 7 TeV. The data were recorded in 2011 with the CMS detector and correspond to an integrated luminosity of 5 fb−1. The Z(ℓℓ) + b-jets cross sections (where ℓℓ = μμ or ee) are measured separately for a Z boson produced with exactly one b jet ...Journal Article -
Studies of azimuthal dihadron correlations in ultra-central PbPb collisions at √sNN=2.76 TeV
(2014)Journal of High Energy PhysicsAzimuthal dihadron correlations of charged particles have been measured in PbPb collisions at sNN−−−−√ = 2.76TeV by the CMS collaboration, using data from the 2011 LHC heavy-ion run. The data set includes a sample of ultra-central (0-0.2% centrality) PbPb events collected using a trigger based on total transverse energy in the hadron forward calorimeters and the total multiplicity of pixel clusters in the silicon pixel tracker. A total ...Journal Article -
Search for jet extinction in the inclusive jet-pT spectrum from proton-proton collisions at √s= 8TeV
(2014)Physical Review DThe first search at the LHC for the extinction of QCD jet production is presented, using data collected with the CMS detector corresponding to an integrated luminosity of 10.7 fb−1 of proton-proton collisions at a center-of-mass energy of 8 TeV. The extinction model studied in this analysis is motivated by the search for signatures of strong gravity at the TeV scale (terascale gravity) and assumes the existence of string couplings in the ...Journal Article