The Decay Rate Asymmetry of the Top Quark

Abstract

The asymmetries ${\mathcal{A}}_k\equiv [\Gamma (\text{twddec})-\Gamma (\text{tbwddec})]/[\Gamma (\text{twddec})+\Gamma (\text{tbwddec})]$ in the partial widths of the top quark decays are discussed within the Standard Model (SM), the Two-Higgs-Doublet Model (2HDM) and supersymmetric extensions 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 ${\mathcal{A}}_b$ can be substantial, $\mathcal{O}({\alpha }_{QCD})$, provided the CP-violating phase of gluino-top-stop couplings is not suppressed. Within the SSM ${\mathcal{A}}_b$ is generated by the vertex corrections.

Comments: 9 pages, 3 figures (not included, postscript files available when requested). CERN-TH.6941/93,UICHEP-TH/93-15