Leptonic decay of heavy leptons

The energy-angle distribution of a light charged lepton $l$ from the decay of an arbitrary polarized heavy charged lepton $L$, $L^{-}\to {\nu }_L+{\overline{\nu }}_l+l^{-}$, is derived assuming that (1) the mass of ${\nu }_L$ is not zero and (2) the coupling of $\mathrm{WL}{\nu }_L$ is some combination of $V$ and $A$. The case when ${\nu }_L$ and ${\overline{\nu }}_l$ are identical is also discussed.