VMD, chiral loops, sigma-meson, and omega-rho mixing in omega-->pi⁰ pi⁰ gamma decay

In an attempt to explain the latest experimental result about the branching ratio of $\omega\to \pi^0\pi^0\gamma$ decay we reexamine the decay mechanism of this decay in a phenomenological framework in which the contributions of VMD, chiral loops, $\sigma$-meson intermediate state amplitudes and the effects of $\omega-\rho$ mixing are considered. We conclude that in order to obtain the experimental value of the branching ratio $B(\omega\to \pi^0\pi^0\gamma)$ $\sigma$-meson amplitude which makes a substantial contribution should be included into the reaction mechanism and the effects of $\omega-\rho$ mixing should be taken into account. We also estimate the coupling constant $g_{\omega\sigma\gamma}$ as $g_{\omega\sigma\gamma}=0.11$ which is much smaller than the values suggested by light cone QCD sum rules calculations.