Hadronic Corrections at O(alpha^2) to the Energy Spectrum of Muon Decay
  We consider the impact of O(alpha^2) hadronic corrections to the energy spectrum of the decay electron in muon decay. We find that the correction can be described, within good approximation, by a linear function in the electron energy. Explicit expressions for the form factors needed in an approach based on dispersion integrals are given. 
A.I.Davydychev, K.Schilcher and H.Spiesberger