Browsing by Author "Goshaw, Alfred"
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Item Open Access Gauge Boson Coupling Measurements in Final States of W Boson Produced with Additional Photons with The ATLAS Detector(2015) Liu, MiaoyuanA first measurement of pp -> Wγγ+X production cross section and the process of vector boson scattering producing Wγ, using the 20.3fb-1 dataset collected by the ATLAS detector from the proton-proton collisions at the Large Hadron Collide (LHC) located in CERN, are presented in this thesis.
Item Open Access Measurement of Z +γ Production and Search for Anomalous Triple Gauge Couplings in Proton-antiproton Collisions at √S = 1.96 Tev(2008-03-19) Deng, JianrongWe present a measurement of ppbar->Zγ + X -> e+e-γ + X production using proton-antiproton collision data collected at the Collider Detector at Fermilab at a center of mass energy of 1.96 TeV. Zγ production provides a direct test of the triple neutral gauge couplings. A measurement of Zγ production cross section and search for anomalous ZZγ and Zγγ couplings are presented. The data presented are from 1.1 fb-1 of ppbar integrated luminosity collected at the CDF Detector. Electrons from Z decays are selected with Et > 20 GeV. Photons (Et > 7 GeV) are required to be well-separated from the electrons. There are 390 eeγ candidate events found with 1.1 fb-1 of data, compared to the SM prediction of 375.3 à ± 25.2 events. The Standard Model prediction for the cross section for ppbar-> e+e-γ + X production at √s = 1.96 TeV is 4.5 à ± 0.4 pb. The measured cross section is 4.7 à ± 0.6 pb. The cross section and kinematic distributions of the eeγ events are in good agreement with theoretical predictions. Limits on the ZZγ and Zγγ couplings are extracted using the photon Et distribution of eeγ events with Meeγ > 100 GeV/c2. These are the first limits measured using CDF Run II data. These limits provide important test of the interaction of the photon and the Z boson.Item Open Access Search for Heavy Boson Resonances in Final States with a W or Z Boson and a Photon Using 139 \fb of Proton-Proton Collision Data at sqrt(s) = 13 TeV Collected with the ATLAS(2020) Feng, MinyuThis thesis presents a search for boson resonances that decay into an energetic photon and the Standard Model's W or Z boson: $X \to W\gamma$ and $X \to Z\gamma$. The dataset used for the measurement was collected at the CERN Large Hadron Collider during a run period from 2015 to 2018. The proton-proton collision center-of-mass energy was 13 TeV with a useful integrated luminosity recorded using the ATLAS detector of 139 \fb. New particle identification techniques are employed, and event selection criteria are optimized to improve the search sensitivity. No significant deviations from the Standard Model predictions are observed over a $W\gamma$ and $Z\gamma$ mass range from 1.0 to 6.8 TeV. The data are used to set limits with 95\% confidence level on the production cross section of massive bosons that are predicted by various extensions of the Standard Model's theory of elementary particles.
Item Open Access Search for New Resonance X->W Gamma and Standard Model W Gamma Production Using Deep Learning Techniques(2018-05-10) Tang, WeiThe Standard Model is by far the most encompassing physics theory. With the recent discovery of the Higgs Boson, the Standard Model has performed extremely well when confronted with experimental data. However, the theory is intrinsically not complete. Extensions of the Standard Model predict new resonances decaying to a W boson and a photon. This thesis presents a search for such resonances produced in proton-proton collisions at 13 TeV using a dataset with an integrated luminosity of 36.1 fb−1 collected by the ATLAS detector at the Large Hadron Collider. The W bosons are identified through their hadronic decay channels. The data are found to be consistent with the expected background in the entire mass range investigated. Upper limits are set on the production cross section times decay branching ratio to W + gamma of new resonances with mass between 1.0 and 6.8 TeV. The second part of this thesis looks at the extraction of the Standard Model W + gamma production. The main background noise for the extraction comes from the Standard Model production of gamma and jets. In order to streamline and improve the accuracy of the event filtering process, this thesis developed a deep neural net classifier to identify signal and background decay products and improved the signal to noise ratio.