292 research outputs found

    Search for contact interactions in the dimuon channel in p-p collisions at sqrt(s) = 7 tev at cms

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    The standard model (SM) fails to explain the variety of observed quark and lepton flavors and their masses suggesting that there might exist a more fundamental basis. If quarks and leptons are composite particles made up of more basic constituents, a new physics interaction in the form of a four-fermion contact interaction arises between them. Experimentally the signal is manifest as a deviation from the SM prediction in the high-mass tail for the invariant mass distribution of the opposite-sign dimuon pairs. The Large Hadron Collider (LHC) experiment at the Center for European Nuclear Research (CERN) is built to explore new physics possibilities from proton-proton collisions occurring at the world\u27s highest center-of-mass energy. This thesis discusses in detail a search strategy for a new physics possibility based on a left-handed current model of contact interactions. Based on 5.3 inverse femtobarns of 2011 LHC data as collected by the Compact Muon Solenoid (CMS) detector, exclusion lower limits at 95% confidence level are set on the compositeness energy scale for both destructive and constructive interferences of the new physics with the SM Drell-Yan process. These limits form the most stringent limits to date and exceed the current published limits significantly

    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

    Juxtaposing BTE and ATE ‚Äď on the role of the European insurance industry in funding civil litigation