Upsilon production in Z decays

We have searched for evidence of T production in 3.5 million hadronic Z decays collected by the L3 detector at LEP in 1991–1995. No signals are observed for the decay chain Z → TX; T → ℓ+ℓ− (ℓ=e,μ), therefore upper limits at 95% confidence level are set on the following Z branching fractions: Br(Z → T(1S)X) < 5.5 × 10−5; Br(Z → T(2S)X) < 13.9 × 10−5; Br(Z → T(3S)X) < 9.4 × 10−5.