Tests for neutral heavy leptons in multilepton events

If a lepton pair ${\mu }^{-}{\mu }^{+}$ or ${\mu }^{-}{e}^{+}$ in the final state of a neutrino reaction originates in the decay of a neutral heavy lepton, the laboratory energies and angles of the two leptons must satisfy the constraints of locality. We derive bounds on the average variables of the leptons which supplement the energy bounds of Pais and Treiman. For a heavy lepton $L^0$ decaying via a right-handed current ${(L^0,{\mu }^{-})}_R$, the two leptons in the dilepton pair must have identical spectra. The characteristics of the recently observed trimuon events are compared with this expectation.