Evidence for Standard Model Higgs Boson Decays to Tau Lepton Pairs in the ATLAS Detector Supported by a Search in the Fully Hadronic Final State
Author: Edmund Noel Dawe
Publisher:
Published: 2014
Total Pages: 195
ISBN-13:
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Author: Edmund Noel Dawe
Publisher:
Published: 2014
Total Pages: 195
ISBN-13:
DOWNLOAD EBOOKAuthor: Gebrüder Heller
Publisher:
Published: 1995
Total Pages: 6
ISBN-13:
DOWNLOAD EBOOKAuthor: Thomas Schwindt
Publisher:
Published: 2015
Total Pages:
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DOWNLOAD EBOOKAuthor: Michel Trottier-McDonald
Publisher:
Published: 2014
Total Pages: 269
ISBN-13:
DOWNLOAD EBOOKThis thesis reports the search for the Higgs boson decaying to a pair of tau leptons, where one tau decays leptonically and the other decays semi-hadronically. The search was conducted by the ATLAS experiment on the proton-proton collisions supplied by the LHC in 2012. It is complicated by background from a mix of known processes from the Standard Model of Particle Physics. It makes use of boosted decision trees to separate the Higgs signal from the background. The gluon-gluon fusion and the vector boson fusion production mechanisms are searched for separately. The statistical significance of the excess observed over the background-only hypothesis is 3.3 standard deviations, and reaches 4.1 standard deviations when combined with other ditau channels. The observed signal appears fully compatible with the Higgs boson of the Standard Model.
Author: Laura Margaret Dodd
Publisher:
Published: 2018
Total Pages: 0
ISBN-13:
DOWNLOAD EBOOKA search for the standard model (SM) Higgs boson which decays to a pair of [tau] leptons is presented in this thesis using 35.9 f b−1 of 13 TeV data collected in 2016 by the CMS detector at CERN. The final states considered require that (1) one [tau] lepton decays leptonically while the other decays hadronically ([mu][tau]h or e[tau]h), (2) both taus decay hadronically ([tau]h[tau]h) or (3) one tau lepton decays to an electron while the other decays to a muon (e[mu]). This thesis specifically focuses on the details of the semi-hadronic decay channels ([mu][tau]h and e[tau]h), and presents the results of all channels combined. The signal strength, [mu], relative to the expectation for the SM Higgs boson is measured to be [mu] = 1.09+0.27−0.24. An excess is observed (expected) corresponding to 4.9 (4.7) [sigma] using 2016 data. The observed (expected) significance reaches 5.9 (5.9) [sigma] when combined with 7 and 8 TeV data collected at CMS. Subsequently following the SM search, a search for dark matter (DM) is presented and interpreted in two simplified Higgs-portal models: a baryonic dark matter model and a two Higgs-doublet model. In this thesis, the Higgs boson is required to decay to an opposite- sign tau pair. The tau pair final states considered are e[tau]h, [mu][tau]h, and [tau]h[tau]h. The expected 95% confidence level upper limits are produced and compared with the observed limit. No significant deviations beyond the SM prediction are observed.
Author: Jessica Kristina Liebal
Publisher:
Published: 2016
Total Pages:
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DOWNLOAD EBOOKAuthor: Martin B. Einhorn
Publisher: North Holland
Published: 1991
Total Pages: 408
ISBN-13:
DOWNLOAD EBOOKVolume 8.
Author: Thomas Schwindt
Publisher:
Published: 2015
Total Pages:
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DOWNLOAD EBOOKAuthor: Valentina Dutta
Publisher:
Published: 2014
Total Pages: 185
ISBN-13:
DOWNLOAD EBOOKIn this thesis, I describe the search for a Higgs boson through its decay to a pair of tan leptons with the tau-pair subsequently decaying to ail electron, a muon, and neutrinos. The search is performed using data collected from proton-proton collisions by the Compact Muon Solenoid experiment at the Large Hadron Collider, corresponding to 5.0 fb-1 of integrated luminosity recorded at a center-of-mass energy of 7 TeV and 19.7 fb-1 at 8 TeV. The expected significance for a Standard Model Higgs boson signal with a mass of 125 GeV is at the level of 1.2 standard deviations for the electron muon tau-pair decay mode. A mild excess of events is seen above the SM background expectation in this decay mode, consistent with a SM Higgs boson of mass 125 GeV. In combination with results using other tau-pair decay modes, an excess of events above the background expectation is seen at the level of 3.4 standard deviations. This constitutes the first evidence for a Higgs boson to decay to leptons. This thesis also describes an analysis of the data in the context of physics beyond the Standard Model, particularly in the framework of its Minimal Supersymnnetric extension.
Author: Herwig Schopper
Publisher: Springer Nature
Published: 2020
Total Pages: 632
ISBN-13: 3030382079
DOWNLOAD EBOOKThis first open access volume of the handbook series contains articles on the standard model of particle physics, both from the theoretical and experimental perspective. It also covers related topics, such as heavy-ion physics, neutrino physics and searches for new physics beyond the standard model. A joint CERN-Springer initiative, the "Particle Physics Reference Library" provides revised and updated contributions based on previously published material in the well-known Landolt-Boernstein series on particle physics, accelerators and detectors (volumes 21A, B1,B2,C), which took stock of the field approximately one decade ago. Central to this new initiative is publication under full open access