Tau lepton mixing with charginos and its effects on chargino searches at e+e− colliders

In bilinear R-parity violating models where a term ϵ3L3H2 is introduced in the superpotential, the tau lepton can mix with charginos. We show that this mixing is fully compatible with LEP1 precision measurements of the Zττ and Wτντ couplings even for large values of ϵ3 and of the induced vacuum expectation value v3 of the tau-sneutrino. The single production of charginos at e+e− colliders is possible in this case and we present numerical values of the cross-section at LEP1, LEP2 and an NLC. We find maximum values of 10 pb at LEP1 and 1 fb at NLC, while the corresponding values at LEP2 are too small to observe.