Author/Authors :
OPAL Collaboration، نويسنده , , G Alexander، نويسنده , , J Allison، نويسنده , , N. Altekamp، نويسنده , , K. Ametewee، نويسنده , , K.J. Anderson، نويسنده , , S Anderson، نويسنده , , S Arcelli، نويسنده , , S Asai، نويسنده , , D Axen، نويسنده , , G Azuelos، نويسنده , , A.H. Ball، نويسنده , , E Barberio، نويسنده , , R.J. Barlow، نويسنده , , R. Bartoldus، نويسنده , , J.R. Batley، نويسنده , , J Bechtluft، نويسنده , , C Beeston، نويسنده , , T Behnke، نويسنده , , A.N Bell، نويسنده , , et al.، نويسنده ,
Abstract :
Searches for unstable neutral and charged heavy leptons (L0, L±) have been performed using a data sample of 2.6 pb−1 at a centre-of-mass energy of s=130 GeV and 2.6 pb−1 at 136 GeV collected with the OPAL detector at LEP during November 1995. No candidate event was observed. If an unstable Dirac neutral heavy lepton L0 decays only into eW∗, μW∗ or τW∗, the lower limits on its mass at 95% C.L. are 62.5 GeV, 63.0 GeV and 57.4 GeV, respectively. The limits are modified for a Majorana L0 to 51.4 GeV, 52.2 GeV and 44.2 GeV, respectively. For charged heavy leptons, a lower mass limit of 64.5 GeV at 95% C.L. was obtained, if L± decays into a stable heavy neutrino νl and W∗±, and ml± − mνl > 10 GeV. If L± decays through lepton flavour mixing into a massless neutrino νℓ and W∗±, the lower limit on ml± was determined to be 63.9 GeV at 95% C.L.
