2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/226584Following the strategy developed by the ALPHA collaboration, we present a method to compute non-perturbatively the decay constant of a heavy-light meson in HQET including the 1/m corrections. We start by a matching between HQET and QCD in a small volume to determine the parameters of the effective theory non-perturbatively. Observables in the effective theory are then evolved to larger volumes. In two steps a large enough volume is reached to determine the physical decay constant. Some preliminary results in the quenched approximation are shown.7 pages, contribution to the XXV International Symposium on Lattice Field Theory, parallel session "Standard model parameters and renormalization"High Energy Physics - Latticetext