$\text{O}({\text{GF}}^2{\text{Mt}}^4)$ Electroweak Radiative Corrections to the $\text{PZ}\text{Pb}\text{Pbbar}$ Vertex

Abstract

The leading heavy-top two-loop corrections to the \Zbb~vertex are determined from a direct evaluation of the corresponding Feynman diagrams in the large \Mt~limit. %The calculation is done in the naive %dimensional regularization scheme with anticommuting ${\text{ga}}_5$. The leading one-loop top-mass effect is enhanced by $[1+\text{GF}{\text{Mt}}^2(9-{\pi }^2/3)/(8{\pi }^2\sqrt{2})]$. Our calculation confirms a recent result of Barbieri et al.

Comments: 12 pages, 3 figures (postscript files attached), Latex, CERN-TH.6874/93