2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/189308Combining our results for various O(alpha_s^2) corrections to the weak radiative B-meson decay, we are able to present the first estimate of the branching ratio at the next-to-next-to-leading order in QCD. We find BR(B -> X_s gamma) = (3.15 +_ 0.23) x 10^-4 for E_gamma > 1.6 GeV in the B-meson rest frame. The four types of uncertainties: non-perturbative (5%), parametric (3%), higher-order (3%) and m_c-interpolation ambiguity (3%) have been added in quadrature to obtain the total error.4 pages, 4 figures. Version accepted by the PRL. Words disallowed by the journal removed from the title. References updated and a note addedHigh Energy Physics - Phenomenologytext