Quark combinatorics and meson-production ratios in hadronic Z0 decays

A vast body of experimental data accumulated in the past few years in hadronic Z0 decays allows one to check quark-combinatorics relations for a new type of processes-namely, quark jets in the decays Z0 → \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document} $$q\bar q$$ \end{document} → hadrons. In this paper, we review quark-combinatorics rules for the yields of vector and pseudoscalar mesons, V/P, in the central and fragmentation regions of hadronic Z0 decays. It is emphasized that, in the central region, a direct verification of quark-combinatorics rules is rather problematic because of a considerable background associated with the decay of highly excited resonances; however, such a verification is possible in the fragmentation region, at xhadron∼0.5–1, where the contribution of resonance decays is suppressed owing to a fast decrease of the spectra with increasing xhadron. It is shown that, in the fragmentation region, experimental data on ρ0/π0 and p/π+ are in reasonable agreement with the predictions of quark combinatorics. The ratios of the heavy-meson yields, B*/B and D*/D, are also discussed: the data demonstrate good agreement with the quark combinatorial results. We analyze the structure of the suppression parameters for strange-and heavy-quark production in soft processes and estimate their orders of magnitude in multiperipheral processes; the ratio K±/π± at xhadron∼0.5–0.8 and the production probabilities for \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document} $$c\bar c$$ \end{document} and \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document} $$b\bar b$$ \end{document} mesons are in good agreement with the estimates.