Precise determination of the f0(600) and f0(980) pole parameters from a dispersive data analysis

Abstract

We use our latest dispersive analysis of pion-pion scattering data and the very recent Kl4 experimental results to obtain the mass, width and couplings of the two lightest scalar-isoscalar resonances. These parameters are defined from their associated poles in the complex plane. The analytic continuation to the complex plane is made in a model independent way by means of once and twice subtracted dispersion relations for the partial waves, without any other theoretical assumption. We find the f0(600) pole at (457^{+14}_{-13})-i(279^{+11}_{-7}) MeV and that of the f0(980) at (996\pm7)-i(25^{+10}_{-6}) MeV, whereas their respective couplings to two pions are 3.59^{+0.11}_{-0.13} GeV and 2.3\pm0.2 GeV.