2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/195991Two-gluon radiative corrections to the $b\to c\ellν$ decay width have been computed analytically as an expansion in terms of \frac{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 - \frac{m_c}{m_b} << 1. Together they describe the process $b\to c\ellν$ for all mass ratios \frac{m_c}{m_b}.9 pages, 4 figures, submitted to Phys. Rev. DHigh Energy Physics - Phenomenologytext