39 research outputs found

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

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

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    Measurement of the production cross section for a W boson and two b jets in pp collisions at root s=7 TeV

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

    Searches for light- and heavy-flavour three-jet resonances in pp collisions at root s=8 TeV

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

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    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

    MESA Status of the Implementation of the MicroTCA.4 based LLRF Control System

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    MESA at the Institut fĂŒr Kernphysik KPH at Johannes Gutenberg UniversitĂ€t Mainz is a multi turn energy recovery linac ERL , aiming to serve as user facility for particle physics experiments. The RF accelerating systems of MESA consist of four 9 cell TESLA superconducting cavities, four normal conducting NC pre accelerator cavities, two NC buncher cavities and two NC chopper cavities. They operate in continuous wave CW mode. In order to control the radio frequency RF amplitude and phase within the 12 cavities with the required accuracy and stability in the range of better than 0.01 and 0.01 , the MicroTCA.4 based digital low level RF LLRF control system based on the development at DESY, Hamburg will be well adapted for the MESA cavities. In this paper, we describe the theoretical modelling of superconducting cavity and PID controller in SIMULINK which is useful to find the suitable control parameter for the PID controller and to predict the system performance. The progress to date of the implementation and tests of the LLRF system at MESA will also be presente

    Breast Density Segmentation Using Texture

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