2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/190597We reexamine the charm contribution to atmospheric lepton fluxes in the context of perturbative QCD. We include next-to-leading order corrections and discuss theoretical uncertainties due to the extrapolations of the gluon distributions at small-x. We show that the charm contribution to the atmospheric muon flux becomes dominant over the conventional contribution from pion and kaon decays at energies of about 10^5 GeV. We compare our fluxes with previous calculations.19 pages, latex, revtex, psfigHigh Energy Physics - Phenomenologytext