Peláez Sagredo, José Ramón2023-06-202023-06-202007978-0-7354-0396-310.1063/1.2714349https://hdl.handle.net/20.500.14352/53483ISSN: 0094-243X ©2007 Amer Inst Physics. Conference on Quark Confinement and the Hadron Spectrum (7. 2006. Ponta Delgada, Portugal). I thank the organization staff, and particularly E. Ribeiro, for creating such a nice working environment and offering me the chance to participate in this wonderful Conference.Dispersive approaches provide model independent description of meson-meson scattering. We first review here the use of dispersion relations to obtain a model independent unitarization of Chiral Perturbation Theory amplitudes, that establish the existence of light scalar mesons and whose leading 1/N_c behavior suggest they ahve a non q q̅ dominant component. We also review the forward dispersion relation checks on conflicting experimental data and the resulting very precise pi pi scattering scattering amplitudes.engbook parthttp://dx.doi.org/10.1063/1.2714349http://scitation.aip.orgopen access51-73Perturbation-theoryπ πScatteringStatesFísica-Modelos matemáticosFísica matemática