Limits on leptonic right-handed currents in E6 theories.

Abstract

With a view to obtaining limits on right-handed charged-current weak interactions produced by mixing between the usual leptons and the extra leptons that occur in the 27 representation of ${\mathrm{E}}_{6}$, we reexamine various parameters which are sensitive to the admixture of right-handed currents (RHC's) in (a) muon decay, (b) nuclear \ensuremath{\beta} decay, (c) inverse muon decay, and (d) leptonic decays of \ensuremath{\tau}. The limits on the RHC's admixture parameter \ensuremath{\Vert}sin${\ensuremath{\theta}}_{R}^{l}$sin${\ensuremath{\varphi}}_{R}^{l}$\ensuremath{\Vert}, where ${\ensuremath{\theta}}_{R}^{l}$ (${\ensuremath{\varphi}}_{R}^{l}$) are the mixing angles for right-handed charged (neutral) leptons, are obtained by making use of the presently available experimental data on the processes (a)--(d). For the e and \ensuremath{\mu} families, the best limits (90% C.L.) are found to be \ensuremath{\Vert}sin${\ensuremath{\theta}}_{R}^{e}$sin${\ensuremath{\varphi}}_{R}^{e}$\ensuremath{\Vert}\ensuremath{\le}0.047 and \ensuremath{\Vert}sin${\ensuremath{\theta}}_{R}^{\ensuremath{\mu}}$sin${\ensuremath{\varphi}}_{R}^{\ensuremath{\mu}}$\ensuremath{\Vert}\ensuremath{\le}0.035, respectively. For the \ensuremath{\tau} family, we obtain the limit (90% C.L.) \ensuremath{\Vert}sin${\ensuremath{\theta}}_{R}^{\ensuremath{\tau}}$sin${\ensuremath{\varphi}}_{R}^{\ensuremath{\tau}}$\ensuremath{\Vert}\ensuremath{\le}0.38. AE