With use of SU(4) as a spectrum-generating group, the radiative decay rates of the charmed vector mesons and of $J\left(\psi \right)$ are calculated. With the known decay rates of the "old" mesons $\Gamma (\omega \to \pi \gamma )$, $\Gamma (\varphi \to \eta \gamma )$, $\Gamma (\rho \to \pi \gamma )$, and $\Gamma (K^{0*}\to K^0\gamma )$ as input, one obtains $\Gamma (K^{+*}\to K^{+}\gamma )=2.6\mathrm{}$ keV, $\Gamma (\omega \to \eta \gamma )=220\mathrm{}$ eV, $\Gamma (\rho \to \eta \gamma )=4.8\mathrm{}$ keV, $\Gamma (\psi \to \chi \gamma )=1.6\mathrm{}$ keV, $\Gamma (D^{0*}\to D^0\gamma )=350\mathrm{}$ eV, and $\Gamma (D^{+*}\to D^{+}\gamma )=22\mathrm{}$ eV.

• Received 5 November 1976

DOI:https://doi.org/10.1103/PhysRevLett.38.629