Higher Order Corrections to the Hadronic Higgs Decay

A Higgs boson in the intermediate mass range is considered. An effective Lagrangian approach is used in order to evaluate the top-induced QCD corrections of order $\alpha_s^3$ to the decay into light quarks and $O(\alpha_s^4)$ corrections to the gluonic decay mode. The connection to the decoupling relations for $\alpha_s$ and the light quark masses is discussed.Comment: 5 pages (Latex), 5 figures (Postscript), to appear in the Proceedings of the International Europhysics Conference on High Energy Physics, Jerusalem, Israel, 19 - 26 August 199

Hadronic contribution to α(MZ2)\alpha(M_Z^2) and the anomalous magnetic moment of the muon

In this contribution recent developments are discussed which lead to a significant reduction of the error for $\alpha(M_Z^2)$ and $(g-2)_\mu$.Comment: 6 pages, Talk presented at the 17th International Workshop on Weak Interactions and Neutrinos (WIN99), Cape Town, South Africa, January 24--30, 199

O(\alpha_s^2) Corrections to Top Quark Production at e+e−e^+e^- Colliders

In this article we evaluate mass corrections up to $O((m^2/q^2)^6)$ to the three-loop polarization function induced by an axial-vector current. Special emphasis is put on the evaluation of the singlet diagram which is absent in the vector case. As a physical application $O(\alpha_s^2)$ corrections to the production of top quarks at future $e^+e^-$ colliders is considered. It is demonstrated that for center of mass energies $\sqrt{s} >~ 500$ GeV the inclusion of the first seven terms into the cross section leads to a reliable description.Comment: LaTeX, 13 pages, 10 figures included as ps-files. The complete paper, including figures, is also available via anonymous ftp at ftp://ttpux2.physik.uni-karlsruhe.de/ , or via www at http://www-ttp.physik.uni-karlsruhe.de/cgi-bin/preprints

Complete Corrections of O(\alpha\alpha_s) to the Decay of the Z Boson into Bottom Quarks

For the vertex corrections to the partial decay rate $\Gamma(Z \to b\bar{b})$ involving the top quark only the leading terms of order $\alpha\alpha_s$ in the $1/M_t$ expansion are known. In this work we compute the missing next-to-leading corrections. Thus at $O(\alpha\alpha_s)$ the complete corrections to the decay of the Z boson into bottom quarks are at hand.Comment: Latex, 11 pages, 1 figure included as ps-file. Two references changed. The complete paper is also available via anonymous ftp at ftp://ttpux2.physik.uni-karlsruhe.de/ttp97/ttp97-52/ or via www at http://www-ttp.physik.uni-karlsruhe.de/cgi-bin/preprints