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

TL;DR

This study analyzes Sigma-antihyperon correlations in Z0 decays at LEP to investigate baryon production mechanisms, finding that the diquark fragmentation model without popcorn is strongly disfavored and highlighting uncertainties in previous popcorn mechanism studies.

Contribution

It introduces a model-independent method based on quantum number correlations to study baryon formation and provides evidence against the diquark fragmentation model without popcorn.

Findings

Diquark fragmentation without popcorn is disfavored at 3.8 sigma.

Quantum number correlation method reduces model dependence.

Previous popcorn mechanism studies are inconclusive with parameter uncertainties.

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 Sigma-hyperons whose baryon number is compensated by the production of a Sigma-, Lambda or 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. The diquark fragmentation 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 are not conclusive if parameter uncertainties are considered.