Massive c-quark contributions to semileptonic b-quark decay near   threshold
  The decay width of b to c,c,c,l,nu has been computed as an expansion in limit (1- 3*(m_c/m_b)) << 1 with zero lepton invariant mass. Considering O(alpha_s^2) corrections to b to c,l,nu with zero invariant lepton mass, inclusion of our result is shown to rectify the disagreement between the expansions around (1-(m_c/m_b)) << 1 and m_c/m_b << 1 at smaller values. 
Matthew Dowling, Alexey Pak