Peláez Sagredo, José Ramón2023-06-192023-06-1920142100-014X10.1051/epjconf/20147303003https://hdl.handle.net/20.500.14352/35023©E D P Sciences. International Conference Meson-Nucleon Physics and the Structure of the Nucleon (MENU) (13. 2013. Roma). Let me thank the organizers for nice Conference and their kid invitation. Work supported by the Spanish Research contract FPA2011-27853-C02-02 and the EU FP7 HadronPhysics3 project.HadronPhysics3 project.In this talk I will very briefly comment on the major revision of the σ or f_0(500) meson in the Review of Particle Physics, driven by new data and rigorous dispersive studies. The long debate on the mass, width and very existence of this meson is settled.engAtribución 3.0 Españahttps://creativecommons.org/licenses/by/3.0/es/journal articlehttp://dx.doi.org/10.1051/epjconf/20147303003http://www.epj-conferences.orgopen access51-73Chiral perturbation-theoryPi-pi scatteringHigh-statisticsGev-cDecayEquationSpanish Research contractFísica-Modelos matemáticosFísica matemática