39 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

    Studies of azimuthal dihadron correlations in ultra-central PbPb collisions at=2.76 TeV

    Get PDF

    Search for single production of scalar leptoquarks in proton-proton collisions at root s=8 TeV

    Get PDF
    Correction DOI:10.1103/PhysRevD.95.039906Peer reviewe

    Observation of a peaking structure in the J/psi phi mass spectrum from B(+/-) to J/psi phi K(+/-) decays

    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+bb¯ 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+bb¯ production cross section in the fiducial region, calculated at the level of final-state particles, is &#963;(pp&#8594;W+bb¯)×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+bb¯ system are in agreement with the predictions of a simulation using MadGraph and pythia

    Measurements of the t(t)Overbar charge asymmetry using the dilepton decay channel in pp collisions at root s=7 TeV

    Get PDF
    The tt¯ charge asymmetry in proton-proton collisions at s&#8730; = 7 TeV is measured using the dilepton decay channel (ee, e &#956; , or &#956;&#956; ). The data correspond to a total integrated luminosity of 5.0 fb &#8722;1 , collected by the CMS experiment at the LHC. The tt and lepton charge asymmetries, defined as the differences in absolute values of the rapidities between the reconstructed top quarks and antiquarks and of the pseudorapidities between the positive and negative leptons, respectively, are measured to be A C = &#8722;0 . 010 ± 0 . 017 (stat . ) ± 0 . 008 (syst . ) and AlepC = 0 . 009 ± 0 . 010 (stat . ) ± 0 . 006 (syst . ). The lepton charge asymmetry is also measured as a function of the invariant mass, rapidity, and transverse momentum of the tt¯ system. All measurements are consistent with the expectations of the standard model

    Search for third-generation scalar leptoquarks in the tτ channel in proton-proton collisions at √s=8 TeV

    Get PDF
    A search for pair production of third-generation scalar leptoquarks decaying to top quark and τ lepton pairs is presented using proton-proton collision data at a center-of-mass energy of s = 8 s√=8 TeV collected with the CMS detector at the LHC and corresponding to an integrated luminosity of 19.7 fb −1 . The search is performed using events that contain an electron or a muon, a hadronically decaying τ lepton, and two or more jets. The observations are found to be consistent with the standard model predictions. Assuming that all leptoquarks decay to a top quark and a τ lepton, the existence of pair produced, charge −1 / 3, third-generation leptoquarks up to a mass of 685 GeV is excluded at 95% confidence level. This result constitutes the first direct limit for leptoquarks decaying into a top quark and a τ lepton, and may also be applied directly to the pair production of bottom squarks decaying predominantly via the R-parity violating coupling λ 333 ′

    Search for W ' -> tb in proton-proton collisions at root s=8 TeV

    Get PDF
    Peer reviewe

    Search for neutral color-octet weak-triplet scalar particles in proton-proton collisions at √s= 8TeV

    Get PDF
    A search for pair production of neutral color-octet weak-triplet scalar particles (Θ0) is performed in processes where one Θ0 decays to a pair of b quark jets and the other to a Z boson plus a jet, with the Z boson decaying to a pair of electrons or muons. The search is performed with data collected by the CMS experiment at the CERN LHC corresponding to an integrated luminosity of 19.7 fb−1 of proton-proton collisions at √s = 8TeV. The number of observed events is found to be in agreement with the standard model predictions. The 95% confidence level upper limit on the product of the cross section and branching fraction is obtained as a function of the Θ0 mass. The 95% confidence level lower bounds on the Θ0 mass are found to be 623 and 426 GeV, for two different octo-triplet theoretical scenarios. These are the first direct experimental bounds on particles predicted by the octo-triplet model. © 2015, The Author(s)

    Measurement of the top-quark mass in all-jets tt events in pp collisions at root = 7 TeV

    Get PDF
    The mass of the top quark is measured using a sample of tt¯ candidate events with at least six jets in the final state. The sample is selected from data collected with the CMS detector in pp collisions at s&#8730;=7 TeV in 2011 and corresponds to an integrated luminosity of 3.54 fb&#8722;1 . The mass is reconstructed for each event employing a kinematic fit of the jets to a tt¯ hypothesis. The top-quark mass is measured to be 173.49±0.69(stat.)±1.21(syst.) GeV. A combination with previously published measurements in other decay modes by CMS yields a mass of 173.54±0.33(stat.)±0.96(syst.) GeV
    corecore