The singular behavior of one-loop massive QCD amplitudes with one   external soft gluon
  We calculate the one-loop correction to the soft-gluon current with massive fermions. This current is process independent and controls the singular behavior of one-loop massive QCD amplitudes in the limit when one external gluon becomes soft. The result derived in this work is the last missing process-independent ingredient needed for numerical evaluation of observables with massive fermions at hadron colliders at the next-to-next-to-leading order. 
Isabella Bierenbaum, Michal Czakon and Alexander Mitov
hep-ph