2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/103412We perform a new numerical analysis of hyperon semileptonic decays emphasizing the systematic uncertainties. The poor understanding of SU(3) symmetry breaking effects at second order in the vector form factor translates into a large error of |V(us)|. Using our determination |V(us)| = 0.226 +/- 0.005 together with those coming from other sources we test the unitarity of the CKM matrix.4 pages, no figures. Talk given at the High-Energy Physics International Conference on Quantum Chromodynamics, 2-9 July (2005), Montpellier (France). References addedHigh Energy Physics - Phenomenologytext