1,744 research outputs found

    Little Higgs Model and Top-like Heavy Quark at CMS

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    The Little Higgs model gives an alternative solution to the fine-tuning problem present in the Standard Model (SM) of strong and electroweak interactions. The model invokes several new particles of TeV mass range, the lightest among them being a heavy quark (T) of charge +2/3. The CMS potential to discover this particle during intial years of LHC running is investigated

    Study of Flavour Changing Neutral Currents in Top Quark Decays with the CMS Detector

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    This paper contains the first realistic estimate for the CMS sensitivity to Flavour Changing Neutral Currents (FCNC) in the top quark sector. The non Standard Model decays t -> Zq and t -> gamma q (q represents c or u quarks) have been studied at sqrts = 14 TeV exploiting leptonic decays of the Z boson and the photon. A realistic detector simulation has been adopted and the most relevant systematic effects have been addressed. The 5- sigma discovery limits for the two decays are BR(t-> qZ) =11.4 x 10^ -4 and BR(t -> gamma q ) =5.7 x 10^ -4, allowing some models of new physics to be tested

    Energy Resolution Performance of the CMS Electromagnetic Calorimeter

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    The energy resolution performance of the CMS lead tungstate crystal electromagnetic calorimeter is presented. Measurements were made with an electron beam using a fully equipped supermodule of the calorimeter barrel. Results are given both for electrons incident on the centre of crystals and for electrons distributed uniformly over the calorimeter surface. The electron energy is reconstructed in matrices of 3 times 3 or 5 times 5 crystals centred on the crystal containing the maximum energy. Corrections for variations in the shower containment are applied in the case of uniform incidence. The resolution measured is consistent with the design goals

    Differential cross section measurements for the production of a W boson in association with jets in proton‚Äďproton collisions at ‚ąös = 7 TeV

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    Measurements are reported of differential cross sections for the production of a W boson, which decays into a muon and a neutrino, in association with jets, as a function of several variables, including the transverse momenta (pT) and pseudorapidities of the four leading jets, the scalar sum of jet transverse momenta (HT), and the difference in azimuthal angle between the directions of each jet and the muon. The data sample of pp collisions at a centre-of-mass energy of 7 TeV was collected with the CMS detector at the LHC and corresponds to an integrated luminosity of 5.0 fb[superscript ‚ąí1]. The measured cross sections are compared to predictions from Monte Carlo generators, MadGraph + pythia and sherpa, and to next-to-leading-order calculations from BlackHat + sherpa. The differential cross sections are found to be in agreement with the predictions, apart from the pT distributions of the leading jets at high pT values, the distributions of the HT at high-HT and low jet multiplicity, and the distribution of the difference in azimuthal angle between the leading jet and the muon at low values.United States. Dept. of EnergyNational Science Foundation (U.S.)Alfred P. Sloan Foundatio

    Optimasi Portofolio Resiko Menggunakan Model Markowitz MVO Dikaitkan dengan Keterbatasan Manusia dalam Memprediksi Masa Depan dalam Perspektif Al-Qur`an