In memory of Paco Ynduráin: A precise determination of ππ scattering from experiment and dispersion relations

This talk is dedicated to the memory of Paco Ynduráin, the original speaker in the conference. After a short account of his scientific career, we briefly review our ongoing collaboration to determine precisely the ππ 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.