Observation of $J/\psi$ production in multihadronic $Z^{0}$ decays

The production of J/ψ mesons in multihadronic Z0 decays has been observed in the e+e− and β+β− final states. From a sample of approximately 45 reconstructed J ψ mesons, the inclusive branching fraction is measured to be Br(Z0→J/ψ + X) = (4.5±0.8±0.4±0.6) × 10−3, where the first error is statistical, the second systematic, and the third error is due to the uncertainty in the leptonic decay rate of the J/ψ. The J/ψ energy distribution is consistent with the distribution expected from B hadron decays. The average B hadron lifetime is calculated from the measured distances between the primary and J/ψ vertices, resulting in τB = 1.32−0.25+0.31±0.15 ps, where the first error is statistical and the second systematic.