A Study of Correlations between Identified Charged Hadrons in Hadronic Z^0 Decays

TL;DR

This study investigates rapidity correlations among identified charged hadrons in Z^0 decays, revealing local quantum number conservation, charge ordering, and differences in heavy and light flavor events, with novel insights from quark hemisphere tagging.

Contribution

It provides the first analysis of signed rapidity distributions using electron beam polarization to probe quantum number ordering in jet fragmentation.

Findings

Short-range charge correlations indicate local quantum number conservation.

Long-range K^+K^- correlations are prominent at high momentum.

Differences in correlations between heavy and light flavor events align with decay properties.

Abstract

We present a preliminary study of correlations in rapidity between pairs of identified charged pions, kaons and protons using the entire SLD data sample of 550,000 hadronic Z^0 decays. Short range charge correlations are observed between all combinations of these hadron species, indicating local conservation of quantum numbers and charge ordering in the jet fragmentation process. The rapidity range of this effect is found to be independent of particle momentum. A strong long-range K^+K^- correlation is observed at high-momentum and weaker long-range pi^+pi^-, pi^+K^-, pK^- and pp-bar correlations are observed in light flavor events, providing new information on leading particle production in u, d and s jets. The long-range correlations observed in c-cbar and bb-bar events are markedly different and consistent with expectations based on known decay properties of the leading heavy hadrons. In addition, the SLC electron beam polarization is used to tag the quark hemisphere in each event, allowing the first study of rapidities signed such that positive rapidity is along the quark rather than antiquark direction. Distributions of ordered differences in signed rapidity between pairs of particles provide a direct probe of quantum number ordering along the quark-antiquark axis and other new insights into the fragmentation process.