  Hadronic corrections to the muon lifetime are calculated in the Fermi theory
in the presence of QED using dispersion relations. The result, after
convolution of hadron data with the calculated perturbative kernel is
  Delta Gamma_had = -Gamma_0(alpha/pi)^2(0.042)
  where Gamma_0 is the tree-level width. The results are also used to obtain
the corrections to the muon lifetime coming from virtual muon and tau loops
  Delta Gamma_muon
  = Gamma_0(alpha/pi)^2[(16987/576)-(85/36)zeta(2)-(64/3)zeta(3)]
  = -Gamma_0(alpha/pi)^2(0.0364333)
  Delta Gamma_tau = -Gamma_0(alpha/pi)^2)(0.00058)
