269 research outputs found

    Measurement of the mass difference between top quark and antiquark in pp collisions at root s=8 TeV

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    Measurements of the ϒ(1S), ϒ(2S), and ϒ(3S) differential cross sections in pp collisions at s=7TeV

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    Differential cross sections as a function of transverse momentum pTpT are presented for the production of ϒ(nS)ϒ(nS) (n = 1, 2, 3) states decaying into a pair of muons. Data corresponding to an integrated luminosity of 4.9View the MathML sourcefb−1 in pp collisions at View the MathML sources=7TeV were collected with the CMS detector at the LHC. The analysis selects events with dimuon rapidity |y|<1.2|y|<1.2 and dimuon transverse momentum in the range View the MathML source10<pT<100GeV. The measurements show a transition from an exponential to a power-law behavior at View the MathML sourcepT≈20GeV for the three ϒ states. Above that transition, the ϒ(3S)ϒ(3S) spectrum is significantly harder than that of the ϒ(1S)ϒ(1S). The ratios of the ϒ(3S)ϒ(3S) and ϒ(2S)ϒ(2S) differential cross sections to the ϒ(1S)ϒ(1S) cross section show a rise as pTpT increases at low pTpT, then become flatter at higher pTpT

    An embedding technique to determine ττ backgrounds in proton-proton collision data

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

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    Constraints on the Higgs boson width from off-shell production and decay to Z-boson pairs

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    Constraints are presented on the total width of the recently discovered Higgs boson, &#915;H , using its relative on-shell and off-shell production and decay rates to a pair of Z bosons, where one Z boson decays to an electron or muon pair, and the other to an electron, muon, or neutrino pair. The analysis is based on the data collected by the CMS experiment at the LHC in 2011 and 2012, corresponding to integrated luminosities of 5.1 fb&#8722;1 at a center-of-mass energy s=7 TeV and 19.7 fb&#8722;1 at s=8 TeV . A simultaneous maximum likelihood fit to the measured kinematic distributions near the resonance peak and above the Z-boson pair production threshold leads to an upper limit on the Higgs boson width of &#915;H<22 MeV at a 95% confidence level, which is 5.4 times the expected value in the standard model at the measured mass of mH=125.6 GeV

    Search for new phenomena in monophoton final states in proton-proton collisions at √s=TeV

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    Results are presented from a search for new physics in final states containing a photon and missing transverse momentum. The data correspond to an integrated luminosity of 19.6 fb−1 collected in proton–proton collisions at s=8 TeV with the CMS experiment at the LHC. No deviation from the standard model predictions is observed for these final states. New, improved limits are set on dark matter production and on parameters of models with large extra dimensions. In particular, the first limits from the LHC on branon production are found and significantly extend previous limits from LEP and the Tevatron. An upper limit of 14.0 fb on the cross section is set at the 95% confidence level for events with a monophoton final state with photon transverse momentum greater than 145 GeV and missing transverse momentum greater than 140 GeV

    Search for heavy neutrinos and W bosons with right-handed couplings in proton - proton collisions at \sqrt = 8TeV

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    A search for heavy, right-handed neutrinos, N&#8467; ( &#8467;=e,&#956; ), and right-handed WR bosons, which arise in the left-right symmetric extensions of the standard model, has been performed by the CMS experiment. The search was based on a sample of two lepton plus two jet events collected in proton&#8211;proton collisions at a center-of-mass energy of 8 TeV corresponding to an integrated luminosity of 19.7 fb-1 . For models with strict left-right symmetry, and assuming only one N&#8467; flavor contributes significantly to the WR decay width, the region in the two-dimensional (MWR,MN&#8467;) mass plane excluded at a 95 % confidence level extends to approximately MWR=3.0TeV and covers a large range of neutrino masses below the WR boson mass, depending on the value of MWR . This search significantly extends the (MWR,MN&#8467;) exclusion region beyond previous results. Electronic supplementary material The online version of this article (doi:10.1140/epjc/s10052-014-3149-z) contains supplementary material, which is available to authorized users

    Search for a Higgs boson decaying into γ*γ→ℓℓγ with low dilepton mass in pp collisions at √s=8 TeV

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    A search is described for a Higgs boson decaying into two photons, one of which has an internal conversion to a muon or an electron pair ( ℓℓγ ). The analysis is performed using proton–proton collision data recorded with the CMS detector at the LHC at a centre-of-mass energy of 8 TeV, corresponding to an integrated luminosity of 19.7 fb −1 . The events selected have an opposite-sign muon or electron pair and a high transverse momentum photon. No excess above background has been found in the three-body invariant mass range 12

    Search for light pseudoscalar boson pairs produced from decays of the 125 GeV Higgs boson in final states with two muons and two nearby tracks in pp collisions at √s = 13 TeV

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