Philip Burrows

Abstract:

We have made the first measurement of the double-inclusive B/B̄ energy distribution in e⁺e^- annihilations, using a sample of 400 000 hadronic Z⁰-decay events recorded in the SLD experiment at SLAC between 1996 and 1998. The small and stable SLC beam spot and the CCD-based vertex detector were used to reconstruct B/B̄-decay vertices with high efficiency and purity, and to provide precise measurements of the kinematic quantities used to calculate the B energies in this novel technique. We measured the B/B̄ energies with good efficiency and resolution over the full kinematic range. We measured moments of the scaled energies of the B and B̄ hadrons vs. the opening angle between them. By comparing these results with perturbative QCD predictions we tested the ansatz of factorisation in heavy-quark production. A recent next-to-leading order calculation reproduces the data. © 2003 Elsevier B.V. All rights reserved.

Abstract:

We present improved measurements of the differential production rates of stable charged particles in hadronic Z⁰ decays, and of charged pions, kaons, and protons identified over a wide momentum range using the SLD Cherenkov ring imaging detector. In addition to flavor-inclusive Z⁰ decays, measurements are made for Z⁰ decays into light (u, d, s), c, and b primary flavors, selected using the upgraded vertex detector. Large differences between the flavors are observed that are qualitatively consistent with expectations based upon previously measured production and decay properties of heavy hadrons. These results are used to test the predictions of QCD in the modified leading logarithm approximation, with the ansatz of local parton-hadron duality, and the predictions of three models of the hadronization process. The light-flavor results provide improved tests of these predictions; the heavy-flavor results provide complementary model tests. In addition we have compared hadron and antihadron production in light quark (as opposed to antiquark) jets. Differences are observed at high momentum for all three charged hadron species, providing direct probes of leading particle effects, and stringent constraints on models. © 2004 The American Physical Society.