Three channel model of meson-meson scattering and scalar meson spectroscopy

Abstract

New solutions on the scalar -- isoscalar $ππ$ phase shifts are analysed together with previous $K\bar{K}$ results using a separable potential model of three coupled channels ($ππ$, $K\bar{K}$ and an effective $2π2π$ system). Model parameters are fitted to two sets of solutions obtained in a recent analysis of the CERN-Cracow-Munich measurements of the $π^- p_{\uparrow} \to π^+ π^- n$ reaction on a polarized target. A relatively narrow (90 -- 180 MeV) scalar resonance $f_0(1400-1460)$ is found, in contrast to a much broader ($Γ\approx 500$ MeV) state emerging from the analysis of previous unpolarized target data.