2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/179183We develop a coupled channel unitary approach describing the behavior at higher energies of systems whose low-energy dynamics is given by effective O(p^2) and O(p^4) chiral Lagrangians. Our free parameters are those of the O(p^4) Lagrangian. When applied to the meson-meson interaction, it yields a remarkable agreement with data up to sqrt{s}=1.2 GeV, dynamically generating the sigma, f_0, a_0,rho and K^* resonances. Further applications are also proposed.References corrected, to be published in Physical Review LettersHigh Energy Physics - PhenomenologyNuclear Theorytext