Predictions for anomalous τ⁺τ⁻γ production at LEP 1

Abstract

We calculate distributions for τ⁺τ⁻γ production at LEP 1 taking into account a potentially existing anomalous magnetic moment a _τ of the τ lepton. The existing upper limits for ¦a _τ¦ are known from the dependence of the decay Z ⁰ → τ⁺τ⁻γ on a ²_τ and are of the order of (1–5)%. We show that such limits are also sensitive to linear terms in a _τ, which are of equal importance at ¦a _τ¦ ∼ (1–2)% and dominate below this value. Contributions from an electric dipole moment dτ do not interfere with the electromagnetic vertex or with the anomalous magnetic moment. Appropriate formulae are derived.