2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/196062By combining a recent estimate of the total B-->X_s gamma branching fraction at O(alpha_s^2) with a detailed analysis of the effects of a cut E_gamma>1.6GeV on photon energy, a prediction for the partial B-->X_s gamma branching fraction at next-to-next-to-leading order in renormalization-group improved perturbation theory is obtained, in which contributions from all relevant scales are properly factorized. The result Br(B-->X_s gamma)=(2.98+-0.26)x10^{-4} is about 1.4 sigma lower than the experimental world average. This opens a window for significant New Physics contributions in rare radiative B decays.4 pages, 1 figureHigh Energy Physics - Phenomenologytext