Garcia-Martin, RKamiński, RobertPeláez Sagredo, José Ramón2023-06-202023-06-202009-01-030217-751X10.1142/S0217751X09044140https://hdl.handle.net/20.500.14352/44852©World scientific publ co pte LTD. Conference MESON 2008 (2008.Cracow, Polonia). This work is dedicated to the memory of Prof. F. J. Yndur ain. We thank H. Leutwyler for his comment about the matching condition, and the organizers for creating the nice scientific atmosphere of the event and the Spanish research contracts PR27/05-13955-BSCH, FPA2004-02602, UCM-CAM 910309 and BFM2003-00856 for partialWe review how the use of recent precise data on kaon decays together with forward dispersion relations (FDR) and Roy’s equations allow us to determine the sigma resonance pole position very precisely, by using only experimental input. In addition, we present preliminary results for a modified set of Roy-like equations with only one subtraction, that show a remarkable improvement in the precision around the σ region. We also improve the matching between the parametrizations at low and intermediate energy of the S0 wave, and show that the effect of this on the sigma pole position is negligible.engjournal articlehttp://dx.doi.org/10.1142/S0217751X09044140http://www.worldscientific.comopen access51-73ScatteringRoy's equationsDispersion relationsSigmascalar mesonsFísica-Modelos matemáticosFísica matemática