  We study a vector dominance model which predicts a fairly large number of
currently interesting decay amplitudes of the types S -> \gamma \gamma, V -> S
\gamma and S -> V \gamma, where S and V denote scalar and vector mesons, in
terms of three parameters. As an application, the model makes it easy to study
in detail a recent proposal to boost the ratio Gamma(phi -> f_0 gamma) /
Gamma(phi -> a_0 gamma) by including the isospin violating a_0 - f_0 mixing.
However we find that this effect is actually small in our model.
