Antiproton--proton annihilation into light neutral meson pairs within an effective meson theory

Antiproton–proton annihilation into light neutral mesons in the few GeV energy domain is investigated in view of a global description of the existing data and predictions for future experiments at PANDA, FAIR. An effective meson model earlier developed, with mesonic and baryonic degrees of freedom in $s$, $t$, and $u$ channels, is applied here to ${\pi }^0{\pi }^0$ production. Form factors with logarithmic $s$ and $t(u)$ dependencies are applied. A fair agreement with the existing angular distributions is obtained. Applying SU(3) symmetry, it is straightforward to recover the angular distributions for ${\pi }^0\eta$, and $\eta \eta$ production in the same energy range. A good agreement is generally obtained with all existing data.