Properties of the light scalar mesons face the experimental data on the $ϕ\toπ^0π^0γ$ decay and the $ππ$ scattering

Abstract

The high-statistical KLOE data on the $ϕ\toπ^0π^0γ$ decay are described simultaneously with the data on $ππ$ scattering and the $ππ\to K\bar K$ reaction. The description is carried out taking into account the chiral shielding of the putative $σ(600)$ meson and it's mixing with the well-established $f_0(980)$ meson. It is shown that the data don't contradict the existence of the $σ(600)$ meson and yield evidence in favor of the four-quark nature of the $σ(600)$ and $f_0(980)$ mesons.