13 research outputs found

    Observation of the Production of Three Massive Gauge Bosons at root s=13 TeV

    Get PDF
    The first observation is reported of the combined production of three massive gauge bosons (VVV with V = W, Z) in proton-proton collisions at a center-of-mass energy of 13 TeV. The analysis is based on a data sample recorded by the CMS experiment at the CERN LHC corresponding to an integrated luminosity of 137 fb(-1). The searches for individualWWW, WWZ, WZZ, and ZZZ production are performed in final states with three, four, five, and six leptons (electrons or muons), or with two same-sign leptons plus one or two jets. The observed (expected) significance of the combinedVVV production signal is 5.7 (5.9) standard deviations and the corresponding measured cross section relative to the standard model prediction is 1.02(-0.23)(+0.26). The significances of the individual WWW and WWZ production are 3.3 and 3.4 standard deviations, respectively. Measured production cross sections for the individual triboson processes are also reported

    Search for a light pseudoscalar Higgs boson in the boosted mu mu tau tau final state in proton-proton collisions at root s=13 TeV

    Get PDF
    A search for a light pseudoscalar Higgs boson (a) decaying from the 125 GeV (or a heavier) scalar Higgs boson (H) is performed using the 2016 LHC proton-proton collision data at root s = 13 TeV, corresponding to an integrated luminosity of 35.9 fb(-1), collected by the CMS experiment. The analysis considers gluon fusion and vector boson fusion production of the H, followed by the decay H -> aa -> mu mu tau tau, and considers pseudoscalar masses in the range 3.6 aa -> mu mu tau tau, down to 1.5 (2.0)x10(-4) for m(H) = 125 (300) GeV. Model-dependent limits on B(H -> aa) are set within the context of two Higgs doublets plus singlet models, with the most stringent results obtained for Type-III models. These results extend current LHC searches for heavier a bosons that decay to resolved lepton pairs and provide the first such bounds for an H boson with a mass above 125 GeV.Peer reviewe

    International Nosocomial Infection Control Consortiu (INICC) report, data summary of 43 countries for 2007-2012. Device-associated module

    No full text
    We report the results of an International Nosocomial Infection Control Consortium (INICC) surveillance study from January 2007-December 2012 in 503 intensive care units (ICUs) in Latin America, Asia, Africa, and Europe. During the 6-year study using the Centers for Disease Control and Prevention's (CDC) U.S. National Healthcare Safety Network (NHSN) definitions for device-associated health care–associated infection (DA-HAI), we collected prospective data from 605,310 patients hospitalized in the INICC's ICUs for an aggregate of 3,338,396 days. Although device utilization in the INICC's ICUs was similar to that reported from ICUs in the U.S. in the CDC's NHSN, rates of device-associated nosocomial infection were higher in the ICUs of the INICC hospitals: the pooled rate of central line–associated bloodstream infection in the INICC's ICUs, 4.9 per 1,000 central line days, is nearly 5-fold higher than the 0.9 per 1,000 central line days reported from comparable U.S. ICUs. The overall rate of ventilator-associated pneumonia was also higher (16.8 vs 1.1 per 1,000 ventilator days) as was the rate of catheter-associated urinary tract infection (5.5 vs 1.3 per 1,000 catheter days). Frequencies of resistance of Pseudomonas isolates to amikacin (42.8% vs 10%) and imipenem (42.4% vs 26.1%) and Klebsiella pneumoniae isolates to ceftazidime (71.2% vs 28.8%) and imipenem (19.6% vs 12.8%) were also higher in the INICC's ICUs compared with the ICUs of the CDC's NHSN

    The very forward CASTOR calorimeter of the CMS experiment

    No full text
    International audienceThe physics motivation, detector design, triggers, calibration, alignment, simulation, and overall performance of the very forward CASTOR calorimeter of the CMS experiment are reviewed. The CASTOR Cherenkov sampling calorimeter is located very close to the LHC beam line, at a radial distance of about 1 cm from the beam pipe, and at 14.4 m from the CMS interaction point, covering the pseudorapidity range of −-6.6 <η<\lt\eta\lt −-5.2. It was designed to withstand high ambient radiation and strong magnetic fields. The performance of the detector in measurements of forward energy density, jets, and processes characterized by rapidity gaps, is reviewed using data collected in proton and nuclear collisions at the LHC

    Measurement of prompt D0{\mathrm{D^0}} and D‟0{\mathrm{\overline{D}}{}^0} meson azimuthal anisotropy and search for strong electric fields in PbPb collisions at sNN=\sqrt{s_\mathrm{NN}} = 5.02 TeV

    No full text
    International audienceThe strong Coulomb field created in ultrarelativistic heavy ion collisions is expected to produce a rapidity-dependent difference ( Δv2 ) in the second Fourier coefficient of the azimuthal distribution (elliptic flow, v2 ) between D0 ( u‟c ) and D‟0 ( uc‟ ) mesons. Motivated by the search for evidence of this field, the CMS detector at the LHC is used to perform the first measurement of Δv2 . The rapidity-averaged value is found to be 〈Δv2〉=0.001±0.001(stat)±0.003(syst) in PbPb collisions at sNN=5.02TeV . In addition, the influence of the collision geometry is explored by measuring the D0 and D‟0 mesons v2 and triangular flow coefficient ( v3 ) as functions of rapidity, transverse momentum ( pT ), and event centrality (a measure of the overlap of the two Pb nuclei). A clear centrality dependence of prompt D0 meson v2 values is observed, while the v3 is largely independent of centrality. These trends are consistent with expectations of flow driven by the initial-state geometry

    The very forward CASTOR calorimeter of the CMS experiment

    No full text

    Search for decays of the 125 GeV Higgs boson into a Z boson and a rho or phi meson

    Get PDF
    Decays of the 125 GeV Higgs boson into a Z boson and a ρ0(770) or ϕ(1020) meson are searched for using proton-proton collision data collected by the CMS experiment at the LHC at s√ = 13 TeV. The analysed data set corresponds to an integrated luminosity of 137 fb−1. Events are selected in which the Z boson decays into a pair of electrons or a pair of muons, and the ρ and ϕ mesons decay into pairs of pions and kaons, respectively. No significant excess above the background model is observed. As different polarization states are possible for the decay products of the Z boson and ρ or ϕ mesons, affecting the signal acceptance, scenarios in which the decays are longitudinally or transversely polarized are considered. Upper limits at the 95% confidence level on the Higgs boson branching fractions into Zρ and Zϕ are determined to be 1.04–1.31% and 0.31–0.40%, respectively, where the ranges reflect the considered polarization scenarios; these values are 740–940 and 730–950 times larger than the respective standard model expectations. These results constitute the first experimental limits on the two decay channels

    Measurement of the CPCP-violating phase ϕs\phi_\mathrm{s} in the Bs0→^0_\mathrm{s}\to J/ψ ϕ/\psi\, \phi(1020) →Ό+Ό−\to \mu^+\mu^-K+^+K−^- channel in proton-proton collisions at s=\sqrt{s} = 13 TeV

    No full text
    International audienceThe CP -violating weak phase ϕs and the decay width difference ΔΓs between the light and heavy Bs0 mass eigenstates are measured with the CMS detector at the LHC in a sample of 48500 reconstructed Bs0→J/ψϕ(1020)→Ό+Ό−K+K− events. The measurement is based on a data sample corresponding to an integrated luminosity of 96.4fb−1 , collected in proton-proton collisions at s=13TeV in 2017–2018. To extract the values of ϕs and ΔΓs , a time-dependent and flavor-tagged angular analysis of the ÎŒ+Ό−K+K− final state is performed. The analysis employs a dedicated tagging trigger and a novel opposite-side muon flavor tagger based on machine learning techniques. The measurement yields ϕs=−11±50(stat)±10(syst)mrad and ΔΓs=0.114±0.014(stat)±0.007(syst)ps−1 , in agreement with the standard model predictions. When combined with the previous CMS measurement at s=8TeV , the following values are obtained: ϕs=−21±44(stat)±10(syst)mrad , ΔΓs=0.1032±0.0095(stat)±0.0048(syst)ps−1 , a significant improvement over the 8 TeV result
    corecore