Two-loop QCD corrections to top quark decay
  We present a determination of a new class of Feynman diagrams relevant for second-order QCD corrections to the top quark decay t -> b W. Modern computing techniques allow us to perform a reduction of the original loop integrals to master integrals. We obtain the analytical value of the top decay rate as an expansion around the limit of massless b and W. 
Maciej Slusarczyk