1,087 research outputs found

    Erratum to: Search for dark matter and unparticles in events with a Z boson and missing transverse momentum in proton-proton collisions at √s=13 TeV (JHEP, (2017), 9, (106), 10.1007/JHEP09(2017)106)

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    In the original paper, figure 10 was incorrect. The correct figure is shown below. Additionally, the unparticle entries in table 3, as well as figure 4 and 5 were labelled with incorrect values of ΛU

    Search for vector-like quarks in events with two oppositely charged leptons and jets in proton–proton collisions at √s = 13 TeV

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    A search for the pair production of heavy vectorlike partners T and B of the top and bottom quarks has been performed by the CMS experiment at the CERN LHC using proton–proton collisions at √s = 13 TeV. The data sample was collected in 2016 and corresponds to an integrated luminosity of 35.9 fb−1. Final states studied for TT production include those where one of the T quarks decays via T → tZ and the other via T → bW, tZ, or tH, where H is a Higgs boson. For the BB case, final states include those where one of the B quarks decays via B → bZ and the other B → tW, bZ, or bH. Events with two oppositely charged electrons or muons, consistent with coming from the decay of a Z boson, and jets are investigated. The number of observed events is consistent with standard model background estimations. Lower limits at 95% confidence level are placed on the masses of the T and B quarks for a range of branching fractions. Assuming 100% branching fractions for T → tZ, and B → bZ, T and B quark mass values below 1280 and 1130 GeV, respectively, are excluded

    Combined measurements of Higgs boson couplings in proton- proton collisions at v s=13TeV

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    Combined measurements of the production and decay rates of the Higgs boson, as well as its couplings to vector bosons and fermions, are presented. The analysis uses the LHC proton–proton collision data set recorded with the CMS detector in 2016 at √s = 13 TeV, corresponding to an integrated luminosity of 35.9 fb−1. The combination is based on analyses targeting the five main Higgs boson production mechanisms (gluon fusion, vector boson fusion, and associated production with a W or Z boson, or a top quarkantiquark pair) and the following decay modes: H → γ γ , ZZ, WW, τ τ , bb, and μμ. Searches for invisible Higgs boson decays are also considered. The best-fit ratio of the signal yield to the standard model expectation is measured to be μ = 1.17 ± 0.10, assuming a Higgs boson mass of 125.09 GeV. Additional results are given for various assumptions on the scaling behavior of the production and decay modes, including generic parametrizations based on ratios of cross sections and branching fractions or couplings. The results are compatible with the standard model predictions in all parametrizations considered. In addition, constraints are placed on various two Higgs doublet models

    Search for supersymmetry in final states with photons and missing transverse momentum in proton-proton collisions at 13 TeV

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    Results are reported of a search for supersymmetry in final states with photons and missing transverse momentum in proton-proton collisions at the LHC. The data sample corresponds to an integrated luminosity of 35.9 fb−1 collected at a center-of-mass energy of 13 TeV using the CMS detector. The results are interpreted in the context of models of gauge-mediated supersymmetry breaking. Production cross section limits are set on gluino and squark pair production in this framework. Gluino masses below 1.86 TeV and squark masses below 1.59 TeV are excluded at 95% confidence level

    Measurement of the Z/gamma* -> tau tau cross section in pp collisions at root s=13 TeV and validation of tau lepton analysis techniques

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    A measurement is presented of the Z/γ ∗ → τ τ cross section in pp collisions at √s = 13 TeV, using data recorded by the CMS experiment at the LHC, corresponding to an integrated luminosity of 2.3 fb−1. The product of the inclusive cross section and branching fraction is measured to be σ (pp → Z/γ ∗+X) B(Z/γ ∗ → ττ) = 1848 ± 12 (stat) ± 67 (syst + lumi) pb, in agreement with the standard model expectation, computed at next-to-next-to-leading order accuracy in perturbative quantum chromodynamics. The measurement is used to validate new analysis techniques relevant for future measurements of τ lepton production. The measurement also provides the reconstruction efficiency and energy scale for τ decays to hadrons + ντ final states, determined with respective relative uncertainties of 2.2 and 0.9

    Search for the associated production of the Higgs boson and a vector boson in proton-proton collisions at √s = 13 TeV via Higgs boson decays to τ leptons

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    A search for the standard model Higgs boson produced in association with a W or a Z boson and decaying to a pair of τ leptons is performed. A data sample of proton-proton collisions collected at √ s = 13 TeV by the CMS experiment at the CERN LHC is used, corresponding to an integrated luminosity of 35.9 fb−1 . The signal strength is measured relative to the expectation for the standard model Higgs boson, yielding µ = 2.5 +1.4 −1.3 . These results are combined with earlier CMS measurements targeting Higgs boson decays to a pair of τ leptons, performed with the same data set in the gluon fusion and vector boson fusion production modes. The combined signal strength is µ = 1.24+0.29 −0.27 (1.00+0.24 −0.23 expected), and the observed significance is 5.5 standard deviations (4.8 expected) for a Higgs boson mass of 125 GeV

    Search for Zγ resonances using leptonic and hadronic final states in proton-proton collisions at s√=13 TeV

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    A search is presented for resonances decaying to a Z boson and a photon. The analysis is based on data from proton-proton collisions at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 fb−1, and collected with the CMS detector at the LHC in 2016. Two decay modes of the Z boson are investigated. In the leptonic channels, the Z boson candidates are reconstructed using electron or muon pairs. In the hadronic channels, they are identified using a large-radius jet, containing either light-quark or b quark decay products of the Z boson, via jet substructure and advanced b quark tagging techniques. The results from these channels are combined and interpreted in terms of upper limits on the product of the production cross section and the branching fraction to Zγ for narrow and broad spin-0 resonances with masses between 0.35 and 4.0 TeV, providing thereby the most stringent limits on such resonances

    Search for charged Higgs bosons in the H± → τ ± ντ decay channel in proton-proton collisions at √s = 13 TeV

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    A search is presented for charged Higgs bosons in the H± → τ ± ντ decay mode in the hadronic final state and in final states with an electron or a muon. The search is based on proton-proton collision data recorded by the CMS experiment in 2016 at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 fb−1 . The results agree with the background expectation from the standard model. Upper limits at 95% confidence level are set on the production cross section times branching fraction to τ ± ντ for an H± in the mass range of 80 GeV to 3 TeV, including the region near the top quark mass. The observed limit ranges from 6 pb at 80 GeV to 5 fb at 3 TeV. The limits are interpreted in the context of the minimal supersymmetric standard model m mod− h scenario

    Measurement of the top quark mass in the all- jets final state at root s=13 TeV and combination with the lepton plus jets channel

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    A top quark mass measurement is performed using 35.9fb-1 of LHC proton–proton collision data collected with the CMS detector at s=13TeV. The measurement uses the t t ¯ all-jets final state. A kinematic fit is performed to reconstruct the decay of the t t ¯ system and suppress the multijet background. Using the ideogram method, the top quark mass (m t ) is determined, simultaneously constraining an additional jet energy scale factor (JSF). The resulting value of mt=172.34±0.20(stat+JSF)±0.70(syst)GeV is in good agreement with previous measurements. In addition, a combined measurement that uses the t t ¯ lepton+jets and all-jets final states is presented, using the same mass extraction method, and provides an m t measurement of 172.26±0.07(stat+JSF)±0.61(syst)GeV. This is the first combined m t extraction from the lepton+jets and all-jets channels through a single likelihood function

    Measurement of inclusive very forward jet cross sections in proton-lead collisions at √sNN = 5.02 TeV

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    Measurements of differential cross sections for inclusive very forward jet production in proton-lead collisions as a function of jet energy are presented. The data were collected with the CMS experiment at the LHC in the laboratory pseudorapidity range −6.6 < η < −5.2. Asymmetric beam energies of 4 TeV for protons and 1.58 TeV per nucleon for Pb nuclei were used, corresponding to a center-of-mass energy per nucleon pair of sNN = 5.02 TeV. Collisions with either the proton (p+Pb) or the ion (Pb+p) traveling towards the negative η hemisphere are studied. The jet cross sections are unfolded to stable-particle level cross sections with p T ≳ 3 GeV, and compared to predictions from various Monte Carlo event generators. In addition, the cross section ratio of p+Pb and Pb+p data is presented. The results are discussed in terms of the saturation of gluon densities at low fractional parton momenta. None of the models under consideration describes all the data over the full jet-energy range and for all beam configurations. Discrepancies between the differential cross sections in data and model predictions of more than two orders of magnitude are observed.[Figure not available: see fulltext.]. © 2019, The Author(s)
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