Browsing by Subject "Z Boson"

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    Measurement of the Associated Production of a Z Boson with a J/psi Meson with the CMS Experiment at a Center-of-Mass Energy of 8 TeV
    (2016-09) Turkewitz, Jared
    The associated production of a Z boson and a J/psi meson provides information about the production mechanisms of quarkonium. A measurement of the associated production of a Z boson, which decays to leptons, and a J/psi meson, which decays to muons, relative to the inclusive production of a Z boson, which decays to leptons, is presented. The measurement was made using the full 19.7 inverse femtobarns of proton-proton collision data collected at a center-of-mass energy of 8 TeV by the Compact Muon Solenoid detector at the Large Hadron Collider. The associated production is presented for both prompt and nonprompt J/psi, as a function of the transverse momentum of the J/psi meson. The associated production cross sections of a Z that decays to two muons or to two electrons, and a prompt or nonprompt J/psi that decays to two muons, relative to the inclusive production cross section of a Z that decays to two muons or to two electrons, are measured.
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    Measurement of the phistar distribution of Z bosons decaying to electron pairs with the CMS experiment at a center-of-mass energy of 8 TeV
    (2015-05) Gude, Alexander
    Measurements of the Z boson transverse momentum (Qt) spectrum serves as both a precision test of non-perturbative QCD and helps to reduce the uncertainty in the measurement of the W boson mass. However, Qt is limited at its lowest values by detector resolution, and so a new variable, phistar, which performs better in the low Qt region, is used instead. This thesis presents the first measurement of the normalized differential cross section of Z bosons decaying to electron pairs in terms of phistar at a center-of-mass energy of 8 TeV. The data used in this measurement were collected by the CMS detector at the LHC in 2012 and totaled 19.7/fb of integrated luminosity. The results are compared to predictions from simulation, which are found to provide a poor description of the data.