On-Shell Unitarity Bootstrap for QCD Amplitudes
  We describe the recently developed on-shell bootstrap for computing one-loop amplitudes in non-supersymmetric theories such as QCD. The method combines the unitarity method with loop-level on-shell recursion. The unitarity method is used to compute cut-containing parts of amplitudes, and on-shell recursion is used for the remaining rational terms. 
Carola F. Berger, Zvi Bern, Lance J. Dixon, Darren Forde, David A.   Kosower