On the mass, width and coupling constants of the f0(980)

Using the pole approach we determine the mass and width of the f0(980); in particular, we analyze the possibility that two nearby poles are associated to it. We restrict our analysis to a neighborhood of the resonance, using ππ data for the phase shift and inelasticity, and the invariant mass spectrum of the J/ψ→φππ,φK anti K decays. The formalism we use is based on unitarity and a generalized version of the Breit-Wigner parameterization. We find that a single pole describes the f0(980), the precise position depending upon the ππ data used. As a byproduct, values for the gf0ππ and gf0KantiK coupling constants are obtained. (orig.)