Measurement of $\hat{I}{ž}^{-}/\bar{\hat{I}}{ž}^{+}$ production in jets from $Z$ boson decays with the DELPHI open data

Abstract

The production rates of $\hat{I}{ž}^{-}/\bar{\hat{I}}{ž}^{+}$ baryons in energy-ranked jets produced in $Z\to \text{hadrons}$ decays are measured using $3.2$ million hadronic $Z$ events recorded by the DELPHI experiment. Jets are reconstructed using the Durham algorithm with $y_{\text{cut}}=0.005$. Quark- and gluon-enriched jet samples are obtained by ranking the jet energies in three-jet events. The softest jet are found to produce fewer $\hat{I}{ž}^{-}/\bar{\hat{I}}{ž}^{+}$ and less energetic baryons than the other jets. The ratio of $\hat{I}{ž}^{-}/\bar{\hat{I}}{ž}^{+}$ production rates in gluon and quark jets, each normalized to the corresponding mean charged-particle multiplicity, is measured to be $1.21\pm 0.18(stat.)\pm 0.26(syst.)$. The result is consistent with the JETSET expectation and the OPAL measurements of $K_S^0$ and $\hat{I}›$ productions in $Z$ decays. This study presents the first measurement of the gluon-to-quark production ratio for baryons containing two $s$ quarks, providing new insights into strange-quark production and hadronization. Future $e^{+}{e}^{-}$ colliders such as CEPC and FCCee will provide much larger $Z$-boson samples and will allow far more precise studies of the subject.

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