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 $\omega \to {\pi }^0{\pi }^0\gamma$ 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.

Comments: to be published in Phys. Rev. D