Search for excited taus from Z⁰ decays

Abstract

We have searched for excited taus from Z⁰ decay in the channels e⁺e⁻→ τ∗⁺τ∗⁻→τ⁺τ^-γγ and e⁺e⁻→ ττ∗→τ⁺τ⁻γ, using the L3 detector at LEP. Using the τ∗ pair production channel, we can exclude a τ∗ up to a mass of 45.5 geV at 95% confidence level. We have also determined upper limits on the ττ∗Z⁰ and ττ∗γ couplings as a function of m_τ∗ up to 89.3 GeV.