2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/179157The value of the light quark masses combination $m_u + m_d$ is analized using QCD-Hadron Duality. A detailed analysis of both the perturbative QCD [to four-loops] and the hadronic parametrization needed is done. The result we get is $[m_u + m_d] (1 GeV^2) = (12.8 \pm 2.5)$ MeV ($[m_u + m_d] (4 GeV^2) = (9.8 \pm 1.9)$ MeV) in the $\barMS$ scheme.9 pages, LaTeX, 2 ps figures, uses epsf.sty. To be published in Proceedings of the ``High Energy Conference on Quantum Chromodynamics (QCD '97)'', 3-9 July 1997, Montpellier, FranceHigh Energy Physics - Phenomenologytext