2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/42602We summarize a computation of the leptonic decay constant f_D_s of the D_s-meson in quenched QCD on the lattice. We perform a direct simulation at the masses of the strange and the charm quarks at four different lattice spacings from approximately 0.1 fm to 0.05 fm. Fully non perturbative O(a)-improvement is employed. After taking the continuum limit we arrive at a value of f_D_s=252(9) MeV, when setting the scale with the Kaon decay constant f_K=160 MeV. Setting the scale with the nucleon mass instead leads to a decrease of about 20 MeV of f_D_s.Invited talk at the Workshop on the CKM Unitarity Triangle, IPPP Durham, April 2003 (eConf C0304052). 4 pages LaTeX, 2 eps figuresHigh Energy Physics - PhenomenologyHigh Energy Physics - Latticetext