Complete Two Loop Electroweak Contributions to the Muon Lifetime in the Standard Model

Abstract

An independent result for the two loop fermionic contributions to the muon lifetime in the Standard Model is obtained. Deviations are found with respect to \cite{Freitas:2000gg}, which result in a shift of the W boson mass by approximately -1.3 MeV over the range of Higgs boson masses from 100 GeV to 1 TeV. Supplied with the bosonic contributions from \cite{Awramik:2002wn,Onishchenko:2002ve,Awramik:2002vu}, this shift, due to the complete electroweak contributions, varies from -2.4 MeV to -0.6 MeV. Additionally, a new test of the matching procedure defining the Fermi constant is presented, which uses fermion masses as infrared regulators.

Comments: 11 pages, 5 figures, Tab. 3 corrected, reference added