The process ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{W}^{+}{W}^{\ensuremath{-}}$ is reexamined with the inclusion of mixing between ordinary leptons and exotic leptons of the types (i) mirror, (ii) vector doublet, and (iii) vector singlet. The effects of mixings are discussed in terms of the expected relative deviations from the standard-model predictions for the total cross section, the forward-backward asymmetry, the differential angular distribution for unpolarized $W'\mathrm{s}$, and the inclusive angular distributions for longitudinally ($L$) and transversely ($T$) polarized $W'\mathrm{s}$ with and without charge identification at energies of the CERN collider LEP II ($\sqrt{s}\ensuremath{\approx}190$ GeV). These deviations are evaluated for three extreme cases of mixing: (I) mixing in the neutral-lepton sector only, (II) mixing in the charged-lepton sector only, and (III) equal mixings in both sectors. The expected relative deviations are presented as a function of the scattering angle $\ensuremath{\theta}$ as well as the exotic-neutrino mass ${m}_{N}$ and the square of the mixing angle ${sin}^{2}\ensuremath{\psi}$. For case (I), all three types of exotic leptons have identical mixing effects. For a run of 500-${\mathrm{pb}}^{\ensuremath{-}1}$ data, with ${m}_{N}\ensuremath{\ge}250$ GeV and $\ensuremath{\psi}={10}^{\ifmmode^\circ\else\textdegree\fi{}}$, the expected relative deviations are more than one standard deviation (SD) error in $d\ensuremath{\sigma}(\ensuremath{\theta})$, $d{\ensuremath{\sigma}}_{T}(\ensuremath{\theta})$ for all values of $\ensuremath{\theta}$, in $d{\ensuremath{\sigma}}_{\mathrm{TT}}(\ensuremath{\theta})$ for $cos\ensuremath{\theta}\ensuremath{\ge}0.4$, and in $d{\ensuremath{\sigma}}_{L}(\ensuremath{\theta})$ for $|cos\ensuremath{\theta}|\ensuremath{\le}0.6$. For case (II), the deviations are almost the same for mirror and vector singlet type of exotic leptons. Further, the deviations in $d\ensuremath{\sigma}$, $d{\ensuremath{\sigma}}_{T}$, $d{\ensuremath{\sigma}}_{L}$, $d{\ensuremath{\sigma}}_{\mathrm{TT}}$, and $d{\ensuremath{\sigma}}_{LT+TL}$ are not sensitive to ${m}_{N}$ and $\ensuremath{\theta}$. For a run of 500-${\mathrm{pb}}^{\ensuremath{-}1}$ data, and for ${m}_{N}\ensuremath{\ge}50$ GeV with ${sin}^{2}\ensuremath{\psi}\ensuremath{\approx}0.03$, the expected deviations are more than 2 SD error. For case (III), the mixing effects are negligible for vector doublet type of exotic leptons. For mirror and vector singlet leptons with ${m}_{N}\ensuremath{\ge}50$ GeV and presently allowed upper limits ${sin}^{2}\ensuremath{\psi}=0.01\ensuremath{-}0.06$, the deviations in $d\ensuremath{\sigma}$, $d{\ensuremath{\sigma}}_{T}$, $d{\ensuremath{\sigma}}_{L}$, $d{\ensuremath{\sigma}}_{\mathrm{TT}}$, and $d{\ensuremath{\sigma}}_{LT+TL}$ are between -7.9% and -18.3%, which would be discernible for a run of 500-${\mathrm{pb}}^{\ensuremath{-}1}$ data.
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Oct 1, 1996
Alison Abbott 
Open Access
