title: Four-loop QCD corrections to the electroweak rho parameter.
abstract: The four-loop QCD corrections to the electroweak rho parameter arising from top and bottom quark loops are computed. Specifically we evaluate the missing "nonsinglet" piece. Using algebraic methods the amplitude is reduced to a set of around 50 new master integrals which are calculated with various analytical and numerical methods. The inclusion of the newly completed term halves the final value of the four-loop correction for the minimally renormalized top-quark mass. The predictions for the shift of the weak mixing angle and the W-boson mass are thus stabilized.
authors.affiliation: Institut für Theoretische Teilchenphysik, Universität Karlsruhe, D-76128 Karlsruhe, Germany.
authors.forename: K G
authors.initials: KG
authors.lastname: Chetyrkin
authors.forename: M
authors.initials: M
authors.lastname: Faisst
authors.forename: J H
authors.initials: JH
authors.lastname: Kühn
authors.forename: P
authors.initials: P
authors.lastname: Maierhöfer
authors.forename: C
authors.initials: C
authors.lastname: Sturm