Assuming that leptons heavier than muons exist in nature, we consider their decay modes and the correlations between the decay products of $l^{+}$ and $l^{-}$ in the colliding-beam experiment: $e^{+}+e^{-}\to l^{+}+l^{-}$. Far above the threshold, the helicities of $l^{+}$ and $l^{-}$ tend to be opposite to each other. Near the threshold the directions of spins of $l^{+}$ and $l^{-}$ prefer to be parallel to each other, and the sum of the two spins prefers to be either parallel or anti-parallel to the direction of the incident electron. Because the parity conservation is violated maximally in the decays of $l^{+}$ and $l^{-}$, the angular distributions of decay products depend strongly on the spin orientation of the heavy leptons. Since the spins of $l^{+}$ and $l^{-}$ are strongly correlated in the production, we found a strong correlation between the energy-angle distributions of the decay products of $l^{+}$ and $l^{-}$. The decay widths of $l^{-}$ into channels ${\nu }_l{\overline{\nu }}_e{e}^{-}$, ${\nu }_l{\overline{\nu }}_{\mu }{\mu }^{-}$, ${\nu }_l{\pi }^{-}$, ${\nu }_l{K}^{-}$, ${\nu }_l{\rho }^{-}$, ${\nu }_l{K}^{*}$, ${\nu }_l{A}_1$, ${\nu }_{l}Q$, and ${\nu }_l+\mathrm{hadron}$ continuum as functions of the mass of $l^{-}$ are estimated.

• Received 22 July 1971

DOI:https://doi.org/10.1103/PhysRevD.4.2821