Complete 2-Loop Quantum Electrodynamic Contributions to the Muon Lifetime in the Fermi Model

Precise prediction forMWin the MSSM

“…(1) as well as the (numerically insignificant) term 3m 2 µ /(5M 2 W ) arising from the tree-level W propagator. The precise measurement of the muon lifetime and the equivalently precise calculation of ∆ QED [36,37] thus provide the accurate value G µ = (1.16637 ± 0.00001 × 10 −5 ) GeV −2 .…”

On the precise determination of the Fermi coupling constant from the muon lifetime

“…(2.8) by performing a large momentum expansion of the imaginary part of propagator-type diagrams. The second order corrections to ∆q have been presented recently [10,15] for m e = 0. The result, ignoring the effects of tau loops, is…”

“…The total decay rate may be calculated directly as the imaginary part of muon self-energy diagrams and was done in Ref. [10]. In charge retention order terms in the numerators that are odd in the electron mass lead to a helicity flip along the internal electron line that causes the purely left-handed V−A vertices to annihilate.…”

Electroweak model and constraints on new physics

“…The O(α 2 ) corrections to µ decay have been completed recently [40]. The remaining uncertainty in G F is from the experimental input.…”

“…Martin, Outhwaite, Ryskin [32] 0.02741 ± 0.00019 includes new BES data Burkhardt & Pietrzyk [33] 0.02763 ± 0.00036 PQCD for √ s > 12 GeV de Troconiz & Yndurain [34] 0.02754 ± 0.00010 PQCD for s > 2 GeV 2 Jegerlehner [35] 0.02766 ± 0.00013 converted from MOM scheme (b) The Fermi constant, G F = 1.16637(1) × 10 −5 GeV −2 , determined from the muon lifetime formula [39,40], …”