VMD, chiral loops, sigma-meson, and omega-rho mixing in omega-->pi^0 pi^0 gamma decay

Abstract

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