2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/43452We show that perturbation theory may give reasonable numbers for the decays of the bottomonium and charmonium ground states to $e^+e^-$ and to $γγ$. To reach this conclusion it is important to perform the resummation of logs. In particular, we obtain the value $Γ(η_b (1S) \to γγ)=0.35 \pm 0.1 ({\rm th.}) \pm 0.05 (\lQ)$ KeV.10 pages, 6 figures, Invited talk at the XXVII International Conference of Theoretical Physics, Ustron, Poland, 15-21 September 2003High Energy Physics - Phenomenologytext