Precise determination of the f(0)(600) and f(0)(980) pole parameters from a dispersive data analysis

Abstract

We use our latest dispersive analysis of π π scattering data and the very recent K_(l4) 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 f(0)(600) pole at [457_(-13)^(+14)] – i[279_(-7)^(+11)+ MeV and that of the f(0)(980) at (996 ± 7) – i[25_(-6)^(+10)] MeV, whereas their respective couplings to two pions are 3.59_(-0.13)^(+0.11) and 2.3 ± 0.2 GeV.