Inclusive Σ + and Σ 0 production in hadronic Z decays

We report on measurements of the inclusive production rate of Σ + and Σ 0 baryons in hadronic Z decays collected with the L3 detector at LEP. The Σ + baryons are detected through the decay Σ + →pπ 0 , while the Σ 0 baryons are detected via the decay mode Σ 0 →Λγ. The average numbers of Σ + and Σ 0 per hadronic Z decay are measured to be: (N Σ + )+ N Σ + )=0.114 ±0.011 stat ±0.009 syst (N Σ° )+N Σ° )=0.095±0.015 stat ±0.013 syst .These rates are found to be higher than the predictions from Monte Carlo hadronization models and analytical parameterizations of strange baryon production.