Production of pi+, K+, K0, K*0, phi, p and Lambda-0 in Hadronic Z0 Decays

TL;DR

This paper measures hadron production in Z0 decays, testing QCD predictions and fragmentation models, and explores flavor and momentum dependencies to understand the hadronization process.

Contribution

It provides detailed measurements of hadron production cross sections and ratios in Z0 decays, offering new insights into flavor dependence and strangeness suppression in fragmentation.

Findings

Flavor dependence observed in hadron production

Differences between hadron and antihadron production at high x_p

Evidence that high-momentum hadrons are more likely to contain primary quarks

Abstract

We have measured the differential production cross sections as a function of scaled momentum x_p=2p/E_cm of the identified hadron species pi+, K+, K0, K*0, phi, p, Lambda0, and of the corresponding antihadron species in inclusive hadronic Z0 decays, as well as separately for Z0 decays into light (u, d, s), c and b flavors. Clear flavor dependences are observed, consistent with expectations based upon previously measured production and decay properties of heavy hadrons. These results were used to test the QCD predictions of Gribov and Lipatov, the predictions of QCD in the Modified Leading Logarithm Approximation with the ansatz of Local Parton-Hadron Duality, and the predictions of three fragmentation models. Ratios of production of different hadron species were also measured as a function of x_p and were used to study the suppression of strange meson, strange and non-strange baryon, and vector meson production in the jet fragmentation process. The light-flavor results provide improved tests of the above predictions, as they remove the contribution of heavy hadron production and decay from that of the rest of the fragmentation process. In addition we have compared hadron and antihadron production as a function of x_p in light quark (as opposed to antiquark) jets. Differences are observed at high x_p, providing direct evidence that higher-momentum hadrons are more likely to contain a primary quark or antiquark. The differences for pseudoscalar and vector kaons provide new measurements of strangeness suppression for high-x_p fragmentation products.