The $g_{V\sigma \gamma }$-coupling constants in hadron electrodynamic

Abstract

Recent measurements of the branching ratios for the decays $\omega \to {\pi }^0{\pi }^0\gamma$ and ${\rho }^0\to {\pi }^0{\pi }^0\gamma$ lead to coupling constants of the $V\sigma \gamma$-interaction ($V$ is a vector meson) one order of magnitude smaller than previously assumed to describe the threshold cross section of $\gamma +p\to p+{\rho }^0$ and the HERMES effect. The new $g_{V\sigma \gamma }^2$ couplings are in contradiction with the predictions of the QCD sum rules, but are in good agreement with VDM-estimation of the $\sigma \to \gamma \gamma$-width.

Comments: four figures, twelve pages