Measurement of cross section times branching ratio for W boson + photon and Z boson + photon and search for anomalous W boson-photon and Z boson-photon couplings at 1.8 TeV
Vondracek, Mark Frank
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https://hdl.handle.net/2142/20424
Description
Title
Measurement of cross section times branching ratio for W boson + photon and Z boson + photon and search for anomalous W boson-photon and Z boson-photon couplings at 1.8 TeV
Author(s)
Vondracek, Mark Frank
Issue Date
1994
Doctoral Committee Chair(s)
Liss, Tony M.
Department of Study
Physics
Discipline
Physics
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Physics, Elementary Particles and High Energy
Language
eng
Abstract
Measurements of the production cross section times branching ratio for $W + \gamma$ and $Z + \gamma$ processes, where the W decays into a muon and neutrino and the Z decays into a muon pair, have been made from the analysis of 18.6 $\pm$ 0.7 $pb\sp{-1}$ of high-$P\sb{T}$ muon data from proton-antiproton (pp) collisions. The data were collected with the Collider Detector at Fermilab (CDF) during the 1992-93 run. In a search for central photons ($\vert\eta\vert\ <$ 1.1) with transverse energy above 7 GeV and angular separation from the muon by at least $\Delta R$ = 0.7 we find 7 $W\gamma$ and 4 $Z\gamma$ candidates. This translates into cross section times branching ratios of 9.0 $\pm$ 6.4 pb for the $W\gamma$ process and 6.6 $\pm$ 3.4 pb for the $Z\gamma$ process. Separate measurements were made for photon $E\sb{T}$ values above 11 GeV and 15 GeV. The cross section times branching ratio results were used to calculate a series of cross section ratios. An analysis designed to search for anomalous couplings between the gauge bosons was also carried out using these results. Assuming only one anomalous coupling to be non-zero at a time, the 95% CL limits on $W\gamma$ anomalous couplings are, $-3.7 < \Delta\kappa\ < 3.7, -1.2 < \lambda < 1.2, -3.8 < \tilde\kappa < 3.8$ and $-1.2 < \tilde\lambda <$ 1.2. For $ZZ\gamma$ anomalous couplings the experimental limits are measured to be, at the 95% CL, $-4.6 < h\sbsp{30}{Z}(h\sbsp{10}{Z}) <$ 4.6 and $-1.1 < h\sbsp{40}{Z}(h\sbsp{20}{Z}) <$ 1.1. For $Z\gamma\gamma$ anomalous couplings the experimental limits are measured to be, at, the 95% CL, $-4.9 < h\sbsp{30}{\gamma}(h\sbsp{10}{\gamma}) <$ 4.9 and $-1.2 < h\sbsp{40}{\gamma}(h\sbsp{20}{\gamma}) <$ 1.2. Limits are placed on electromagnetic multipole moments for both the W and Z bosons using the measured limits of the anomalous couplings, and are presented in this thesis. All of the measurements presented in this thesis are consistent with Standard Model expectations.
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