Quark combinatorics and meson-production ratios in hadronic Z 0 decays

Abstract

A vast body of experimental data accumulated in the past few years in hadronic Z 0 decays allows one to check quark-combinatorics relations for a new type of processes-namely, quark jets in the decays Z 0 → \(q\bar q\) → 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 Z 0 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 x hadron∼0.5–1, where the contribution of resonance decays is suppressed owing to a fast decrease of the spectra with increasing x hadron. 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 x hadron∼0.5–0.8 and the production probabilities for \(c\bar c\) and \(b\bar b\) mesons are in good agreement with the estimates.