Search for the scalar $a_0$ and $f_0$ mesons in the reactions $e^+e^-\toγπ^0π^0(η)$

Abstract

It is shown that the reactions $e^+e^-\toγπ^0π^0(η)$ give a good chance for observing scalar $a_0$ and $f_0$ mesons. In the photon energy region less then 100 MeV the vector meson contributions $e^+e^-\to V^0\toπ^0 V'^0\toγπ^0π^0(η)$ are negligible in comparison with the scalar mesons $e^+e^-\toϕ\toγf_0(a_0)\toγπ^0π^0(η)$ for $BR(ϕ\toγf_0(a_0)\toγπ^0π^0(η))$ greater than $5\cdot10^{-6}(10^{-5})$. Using two-channel treatment of the $ππ$ scattering the predictions for $BR(ϕ\toγ(f_0+σ)\toγππ)$ are derived. The four quark model, the model of $K\bar K$ molecule and the$s\bar s$ model of scalar $f_0$ and $a_0$ mesons are discussed.