Two-loop QCD corrections to semileptonic b-quark decays near maximum recoil

Two-gluon radiative corrections to the b→cℓν¯_ℓ decay width have been computed analytically as an expansion in terms of (m_c)/(m_b)≪1 in the kinematical limit of zero lepton invariant mass. The obtained results match smoothly with a previously known expansion around (1-(m_c)/(m_b))≪1. Together they describe the process b→cℓν¯_ℓ for all mass ratios (m_c)/(m_b).