Two-loop electroweak parameters

A recent calculation of the electroweak parameter Δr, including the dominant two-loop contributions and resummation of large logarithms, is reformulated in terms of the dressed gauge-boson propagators and extended to the electroweak quantities measured at theZ peak such as the various partial widths and asymmetries. The formalism is simpler and physically more transparent. Large two-loop corrections specific to theZ→bb b¯b¯ partial width are included consistently. A detailed statistical analysis is presented of the implications for the topquark and Higgs-boson masses from the latest precision measurements of theW-boson mass and theZ-boson partial widths