Electron-type neutral heavy lepton and theW-boson mass

Abstract

We comment on the experimental implications of the possible existence of an electron-type neutral heavy lepton ${E}^{0}$ with a mass around 10 GeV at the next generation of ${e}^{+}{e}^{\ensuremath{-}}$ colliding machines with $\sqrt{s}=30\ensuremath{-}40$ GeV. The $e\ensuremath{\mu}$ decay signal from ${E}^{0}\ensuremath{\rightarrow}{e}^{\ensuremath{-}}+{\ensuremath{\mu}}^{+}+{\ensuremath{\nu}}_{\ensuremath{\mu}}$ following the weak production ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{\overline{\ensuremath{\nu}}}_{e}+{E}^{0}$ is almost comparable to the $e\ensuremath{\mu}$ signal from the conventional charged heavy leptons produced via one-photon annihilation. (This is so because the small leptonic branching ratio enters only once for ${E}^{0}$ decay). The collinearity angle distributions of $e\ensuremath{\mu}$ signals from these two processes are quite distinct. The $e\ensuremath{\mu}$ cross section via ${E}^{0}$ production is rather sensitive to the mass of the $W$ boson. The invariant-mass spectrum of $e\ensuremath{\mu}$ and the energy spectra of $e$ and $\ensuremath{\mu}$ also show characteristic behaviors.