A Search for the Charged Higgs Boson Decays of the Top Quark Using Hadronic Decays of the Tau Lepton in Proton-antiproton Collisions at [square Root]s PDF Download

Author: Leslie Stevan Groer
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Category :
Languages : en
Pages : 598

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Languages : en
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The Standard Model predicts the existence of one neutral scalar Higgs boson, which is a remnant of the mechanism that breaks the SU(2)[sub L]xU(1)[sub Y] electroweak symmetry and generates masses for the heavy vector bosons and fermions. Many extensions to the Standard Model predict two or more Higgs doublets, resulting in a larger spectrum of Higgs bosons including a charged Higgs boson (H[sup [+-]]). For a light charged Higgs boson mass, the top decay into a charged Higgs boson and bottom quark might occur. This thesis presents results of a direct search for this top quark decay mode via the charged Higgs decay to a tau lepton and tau-neutrino, using the hadronic decays of the tau leptons. The search data consist of 100 pb[sup -1] of Run 1 data collected between 1992-1995 at the CDF detector, from p[anti p] collisions at a center-of-mass energy of 1.8 TeV produced at Fermilab's Tevatron accelerator. A total of seven events are observed in two search channels with an expected background contribution of 7.4[+-]2.0 events coming from fake taus (5.4[+-]1.5), heavy vector boson decays with jets (1.9[+-]1.3) and dibosons(0.08[+-]0.06). Lacking evidence for a signal, we set limits on charged Higgs production at the 95% confidence level in the charged Higgs mass plane versus tan[beta](a parameter of the theory) for a top quark mass of 175 GeV/c[sup 2] and for top production cross sections ([sigma][sub t[anti t]]) of 5.0 and 7.5 pb, assuming the Type-II Two-Higgs-Doublet-Model. For large tan[beta], this analysis excludes a charged Higgs boson of mass below 147(158)GeV/c[sup 2] for [sigma][sub t[anti t]]=5.0(7.5)pb. Using the Standard Model measured top quark cross section from CDF, this limit increases to 168 GeV/c[sup 2] and we also exclude a branching fraction of top decays via this charged Higgs mode of greater than 43% for charged Higgs masses below 168 GeV/c[sup 2].

Author: Brendan Bevensee
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Category :
Languages : en
Pages : 254

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Author: Geum Bong Yu
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Category :
Languages : en
Pages : 364

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ISBN:
Category :
Languages : en
Pages : 204

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In this dissertation we report on the first direct search for charged Higgs bosons in decays of top quarks in p{bar p} collisions at √s = 1.96 TeV. The search uses a data sample with an integrated luminosity of 2.2 fb−1 collected by the CDF II detector at Fermilab and looks for a resonance in the invariant mass distribution of two jets in the lepton+jets sample of t{bar t} candidates. We observe no evidence of charged Higgs bosons in top quark decays; hence 95% C.L. upper limits on the branching ratio are placed at [Beta](t → H+b)

Author:
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Category : Aeronautics
Languages : en
Pages : 704

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Category :
Languages : en
Pages : 204

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In this dissertation we report on the first direct search for charged Higgs bosons in decays of top quarks in p$ar{p}$ collisions at √s = 1.96 TeV. The search uses a data sample with an integrated luminosity of 2.2 fb-1 collected by the CDF II detector at Fermilab and looks for a resonance in the invariant mass distribution of two jets in the lepton+jets sample of t$ar{t}$ candidates. We observe no evidence of charged Higgs bosons in top quark decays; hence 95% C.L. upper limits on the branching ratio are placed at ?(t → H+b) 0.1 to 0.3 for charged Higgs boson masses of 60 to 150 GeV/csup2/sup assuming ?(Hsup+/sup → c$ar{s}$) = 1.0 and ?(t → Wb)+?(t → Hsup+/supb) = 1.0. The upper limits on ?(t → Hsup+

Author: Andrey Elagin
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Languages : en
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A search for the Higgs boson decaying to tau tau using 7.8 fb^-1 of pp collisions at 1.96 TeV collected with CDF II detector is presented. The search is sensitive to four production mechanisms of the Higgs boson: ggH, WH, ZH and VBF. Modes where one tau decay leptonically, and another decay, hadronically, are considered. Two novel techniques are developed and used in the search. A Probabilistic Particle Flow Algorithm is used for energy measurements of the hadronic tau candidates. The signal is discriminated from backgrounds by the Missing Mass Calculator, which allows for full invariant mass reconstruction of tau tau pair. The data are found to be consistent with the background only hypothesis. Therefore a 95% confidence level upper limit on the Standard Model Higgs boson cross section was set. At M_H=120 GeV/c^2 observed limit is 14.9 x sigma_SM x Br(H -> tau tau).

Author: Colin Philip Jessop
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Category : Higgs bosons
Languages : en
Pages : 298

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Author:
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ISBN:
Category :
Languages : en
Pages : 7

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We report on the first direct search for charged Higgs bosons in decays of top quarks in p{bar p} collisions at √s = 1.96 TeV. The search uses a data sample corresponding to an integrated luminosity of 2.2 fb−1 collected by the CDF II detector at Fermilab, and looks for a resonance in the invariant mass distribution of two jets in the lepton+jets sample of t{bar t} candidates. We observe no evidence of charged Higgs bosons in top quark decays. Hence, 95% upper limits on the top quark decay branching ratio are placed at [Beta](t → H+b)