Decays ofL=1mesons toγπ,γρ, andγγ

The importance is stressed of measuring the rate and angular distributions in $f_0\to \gamma \rho \to \gamma {\pi }^{+}{\pi }^{-}$. Predictions are made for this process on the basis of the single-quark-transition hypothesis in terms of the recently measured radiative widths $\Gamma (B\to \gamma \pi )$, $\Gamma (A_{1,2}^{\pm }\to \gamma {\pi }^{\pm })$. Additional predictions, based on vector dominance and measured rates for pion emission, permit the conclusions that $\Gamma (B\to \gamma \pi )=184\mathrm{}\pm 30$ keV, $\Gamma ({A_1}^{\pm }\to \gamma {\pi }^{\pm })=1-1.6\mathrm{}$ MeV, $\Gamma ({A_2}^{\pm }\to \gamma {\pi }^{\pm })=375\mathrm{}\pm 50$ keV, and $\Gamma (f_0\to \gamma \rho )=1.35\mathrm{}\pm 0.2$ MeV. About 10% of this last partial width occurs in $M2\mathrm{}$ and 90% in $E1\mathrm{}$ radiation. The relative sign of the $M2\mathrm{}$ and $E1\mathrm{}$ amplitudes is predicted and one way is shown to measure their ratio. Another application of vector dominance leads to the prediction $\Gamma (f_0\to \gamma \gamma )=7.7\mathrm{}\pm 2$ keV, dominantly in the helicity-2 channel. An intrinsic limitation of vector dominance for heavy-quark systems is noted.