2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/202689We compute the α_s^2β_0 part of the two-loop QCD corrections to the charged lepton spectrum in b \to c \ell \barν_\ell decays and find them to be about 50\% of the first order corrections at all lepton energies, except those close to the end point. Including these corrections we extract the central values \barΛ=0.33 GeV and λ_1=-0.17 GeV^2 for the HQET matrix elements and use them to determine the $\overline{\rm MS}$ b and c quark masses, and |V_{cb}|.15 pages, 1 Postscript figureHigh Energy Physics - Phenomenologytext