Peláez Sagredo, José RamónMartin, R.García, R.Kamiński, RobertYndurain, F.J.2023-06-202023-06-202009-010920-563210.1016/j.nuclphysbps.2008.12.070https://hdl.handle.net/20.500.14352/44856©Elsevier Science Bv. J.R.P. thanks A. Galindo, A. González Arroyo and M.J. Herrero, for kindly providing information about Paco Ynduráin’s career and H. Leutwyler for his comments about the matching of the S0 wave.This talk is dedicated to the memory of Paco Yndurain, the original speaker in the conference. After a short account of his scientific career, we briefly review our ongoing collaboration to determine precisely the pi pi scattering amplitude including the most recent data by means of Forward Dispersion Relations and Roy Equations. A remarkable improvement in precision over the intermediate energy region is obtained by using once-subtracted Roy Equations in addition to the standard twice-subtracted ones.engjournal articlehttp://dx.doi.org/10.1016/j.nuclphysbps.2008.12.070http://www.sciencedirect.com/http://arxiv.org/abs/0810.2204open access51-73Inelastic structure functionsPbarp colliderPhase-shiftssymmetryBehaviorQcdFísica-Modelos matemáticosFísica matemática