385 research outputs found

    Search for supersymmetry in pp collisions with all-hadronic final states using the őĪT variable with the CMS detector at the LHC

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    A search for supersymmetry in the exclusive hadronic and missing energy channel is presented on 5 fb-1 of data collected using the CMS detector at the LHC. The data were produced at a center-of-mass energy of 7 TeV. The kinematic discriminator őĪT is used to select signal events which are then binned in terms of the visible energy per event. The efficiency of the hadronic level one triggers is measured though-out the data taking period and a scheme to reduce the effects of multiple collisions per bunch crossing on the cross section of the trigger paths is studied, implemented and tested in situ. These efficiency measurements are considered in the development of an analysis specific trigger, the performance of which is measured in situ, with the final efficiencies taken into account in the presented analysis. A data driven background estimation method is used to predict the expected yield in the signal regions from Standard Model processes. In the absence of an observed excess, limits are set to the 95% confidence level on the production cross section and masses of new particles. In the context of the Constrained Minimal Supersymmetric Model (CMSSM), squarks and gluinos with a mass of up to 1 TeV are excluded. In terms of simplified models with various light and heavy flavour final states, squarks and gluinos are excluded at a mass of ‚Čą1 TeV for a Lightest Supersymmetric Particle (LSP) mass of up to ‚Čą500 GeV. Natural units (h = c = 1) are used though-out.Open Acces

    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

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