The leptonic decay of neutral vector $\left(J^{P C}=1^{--}\right)$mesons can be pictured as proceeding via a virtual photon,
$$
\mathrm{V}(\mathrm{q} \overline{\mathrm{q}}) \rightarrow \gamma \rightarrow \mathrm{e}^{+} \mathrm{e}^{-} .
$$
The technique for calculating such amplitudes will be explained in succeeding chapters. Here, it suffices to note that the $\mathrm{V}-\gamma$ coupling is proportional to the charge of the quark q. Neglecting a possible dependence on the vector meson mass, show that the leptonic decay widths are in the ratios
$$
\rho: \omega: \phi: \psi=9: 1: 2: 8 \text {. }
$$