2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/199310We evaluate lower bounds on the sum of the up and down quark masses. The bounds follow from the constraints provided by the dispersion relation obeyed by the two--point function of the scalar current density when combined with properties of the scalar spectral function at long--distances and perturbative QCD at short--distances. Our results point to values of $m_u+m_d$ somewhat higher than those reported recently in the literature using lattice QCD simulations.7 pages, 3figures. A few sentences have been added to improve clarity. One reference added. To be published in PLBHigh Energy Physics - Phenomenologytext