The 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.
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