A search for heavy charged and neutral leptons from Z0 decays

A Search for Neutral Heavy Leptons

In e+eannihilations at SPEAR we have searched for narrow neutral resonances in the eT and ~.ln channels for masses between .5 GeV/c 2 and 1.5 GeV/c2. No evidence for such states has been found. Under standard theoretical assumptions for production cross sections and decay branching ratios of heavy leptons a lower limit of 1.2 GeV/c 2 can be set on the mass. *FJork supported by the Energy Resear...

European Organization for Nuclear Research Search for Neutral B Meson Decays to Two Charged Leptons

Search for new Heavy Leptons

A review is given on the search for new heavy leptons in e+eand pj!i collisions. Invited talk at the XXl’Vth International Conference on High Energy Physics, Munich, Germany, August 4-10, 1988 1 5‘ * Wo;k’kpported by the Department of Energy, contract DE-AC03-76SF00515. tM&iling address: DESY F36, Notkestrafie 85, D 2000 Hamburg 52. Bitnet address: user F36WDB at node DHHDESYS. Search for new H...

Some constraints on neutral heavy leptons from flavor-conserving decays of the Z boson.

Small neutrino masses can arise in some grand unified models or superstring theories. We consider a model with an enhanced fermion sector containing Dirac neutral heavy leptons. The dependence on the mass and mixing parameters of these new fermions is investigated for several measurable quantities. We study the flavor-conserving leptonic decays of the Z boson and universal-ity breaking in these...

Neutral Heavy Leptons and Electroweak Baryogenesis

We investigate the possibility that baryogenesis occurs during the weak phase transition in a minimal extension of the Standard Model which contains extra neutral leptons and conserves total lepton number. The necessary CP-violating phases appear in the leptonic Yukawa couplings. We compute the CP-asymmetries in both the neutral and the charged lepton fluxes reflected in the unbroken phase. Usi...