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تسجيل مستخدم جديدThe Significance of the Heavy Top Quark
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E.H. Simmons
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Experiment shows that the top quark is far heavier than the other elementary fermions. This finding has stimulated research on theories of electroweak and flavor symmetry breaking that include physics beyond the standard model. Efforts to accommodate a heavy top quark within existing frameworks have revealed constraints on model-building. Other investigations have started from the premise that a large top quark mass could signal a qualitative difference between the top quark and other fermions, perhaps in the form of new interactions peculiar to the top quark. Such new dynamics may also help answer existing questions about electroweak and flavor physics. This talk explores the implications of the heavy top quark in the context of weakly-coupled (e.g. SUSY) and strongly-coupled (e.g. technicolor) theories of electroweak symmetry breaking.
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On the twentieth anniversary of the observation of the top quark, we trace our understanding of this heaviest of all known particles from the prediction of its existence, through the searches and discovery, to the current knowledge of its production
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We calculate the dominant three body Higgs decays, $H to W^+W^-(Z^0, gamma)$ and $H to toverline{t}(Z^0,gamma ,g)$, in the Standard Model. We find that the branching ratios of these decays are of the order of few percent for large Higgs masses. We co
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The asymmetries ${cal A}_k equiv [Gamma(twddec) -Gamma(tbwddec)] /[Gamma(twddec) + Gamma(tbwddec)]$ in the partial widths of the top quark decays are discussed within the Standard Model (SM), the Two-Higgs-Doublet Model (2HDM) and supersymmetric exte
nsions of the SM (SSM). The leading contributions to these asymmetries in the SM and in the 2HDM are induced by the up-type quark self-energy diagrams and are found to be very small. However, in the SSM, the asymmetry ${cal A}_b$ can be substantial, ${cal O}(alpha_{QCD})$, provided the CP-violating phase of gluino-top-stop couplings is not suppressed. Within the SSM ${cal A}_b$ is generated by the vertex corrections.
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