The model-independent analysis of multi-channel pion-pion scattering and the pion-pion scattering length

The f0 mesons and ππ-scattering length a00 are studyed in a model-independent analysis of data on the isoscalar S-wave processes ππ→ππ,KK¯ including the very precise NA48/2-Collaboration ππ-data and taking the alternative ππ-scattering data by B. Hyams et al.(1973) and by R. Kamiński et al.(2002).