Precise dispersive determination of the f0(600) and f0(980) resonances
  We review our recent dispersive and model independent determination of the lightest two scalars, in terms of poles and residues - or mass, width and coupling- by means of once and twice subtracted Roy equations, using as input constrained fits to data, including the most recent ones from Kl4 decays. We find the f0(600) pole at (457+14-13)-i(279+11-7) MeV and that of the f0(980) at (996+-7)-i(25+10-6) MeV, whereas their respective couplings to two pions are 3.59+0.11-0.13 GeV and 2.3+-0.2 GeV. 
Jose R. Pelaez, R. Garcia Martin, R. Kaminski, J. Ruiz de Elvira
hep-ph nucl-th