Hadronic contributions to the muon lifetime

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 T-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) 0.0365333, Delta Gamma(tau) = - Gamma(0)(alpha/pi)(2) 0.00058. (C) 1998 Elsevier Science B.V. All rights reserved.