Two-loop electroweak top corrections: are they under control?

G. Degrassi; S. Fanchiotti; F. Feruglio; P. Gambino; A. Vicini

doi:10.1016/0370-2693(95)00268-P

paper

Two-loop electroweak top corrections: are they under control?

arXiv:hep-ph/9412380 · doi:10.1016/0370-2693(95)00268-P

Abstract

The assumption that two-loop top corrections are well approximated by the $O (G_{m} u^{2} m t^{4})$ contribution is investigated. It is shown that in the case of the ratio neutral-to-charged current amplitudes at zero momentum transfer the $O (G_{m} u^{2} m t^{2} M_{Z}^{2})$ terms are numerically comparable to the $m_{t}^{4}$ contribution for realistic values of the top mass. An estimate of the theoretical error due to unknown two-loop top effect is presented for a few observables of LEP interest.

13 pages, LaTeX using equations, doublespace, cite macros. Hard copies of the paper including one figure are available from [email protected]