Heavy-to-light decays with a two-loop accuracy
  We present a determination of a new class of three-loop Feynman diagrams describing heavy-to-light transitions. We apply it to find the O(alpha_s^2) corrections to the top quark decay t -> bW and to the distribution of lepton invariant mass in the semileptonic b quark decay b -> ul\nu. We also confirm the previously determined total rate of that process as well as the O(alpha^2) corrections to the muon lifetime. 
Ian Blokland, Andrzej Czarnecki, Maciej Slusarczyk and Fyodor Tkachov