Leptonic CP violation in Z⁰ decays

Abstract

An SU(2)_L⊗U(1)_γ model containing exotic charged leptons can allow sizeable leptonic flavor violations (LFV) and hence rare Z decays into leptons of different flavors. The rates as well as CP-violating asymmetries are constrained using available limits on LFV and data from the CERN e⁺e⁻ collider LEP on Z→l_il_i,l_i=e,μ,τ. Sizeable CP-violating rate asymmetries are theoretically possible in the model and are allowed by the former data. In contrast, the measured leptonic Z widths severely constrain these asymmetries. As a result, an experimental observation of the CP asymmetries in the model seems unlikely with less than 10⁹ Z's.