Σ⁻-antihyperon correlations in Z⁰ decay and investigation of the baryon production mechanism

Abstract

Data collected around $\sqrt{s}=91$  GeV by the OPAL experiment at the LEP e⁺e⁻ collider are used to study the mechanism of baryon formation. As the signature, the fraction of Σ⁻ hyperons whose baryon number is compensated by the production of a $\overline{\Sigma^{-}},\overline{\Lambda}$ or $\overline{\Xi^{-}}$ antihyperon is determined. The method relies entirely on quantum number correlations of the baryons, and not rapidity correlations, making it more model independent than previous studies. Within the context of the JETSET implementation of the string hadronization model, the diquark baryon production model without the popcorn mechanism is strongly disfavored with a significance of 3.8 standard deviations including systematic uncertainties. It is shown that previous studies of the popcorn mechanism with $\Lambda \overline{\Lambda}$ and $\mathrm{p}\uppi \overline{\mathrm{p}}$ correlations are not conclusive, if parameter uncertainties are considered.