Meson-meson scattering: K overlineK-thresholds and f0(980)- a0(980) mixing

We study the influence of mass splitting between the charged and neutral pions and kaons in the Jülich meson exchange model for ππ and πη scattering. The calculations are performed in the particle basis, which permits the use of physical masses for the pseudoscalar mesons and a study of the distinct thresholds associated with the neutral and the charged kaons. Within this model we also investigate the isospin violation which arises from the mass splitting and an apparent violation of G-parity in ππ scattering which stems from the coupling to the K overlineK channel. Non-vanishing cross sections for ππ → π⁰η indicate a mixing of the f₀(980) and a₀(980) states.