Philip Burrows

Abstract:

We present a measurement of the b-quark inclusive fragmentation function in Z0 decays using a novel kinematic B-hadron energy reconstruction technique. The measurement was performed using 350 000 hadronic Z0 events recorded in the SLD experiment at SLAC between 1997 and 1998. The small and stable SLC beam spot and the charge-coupled-device-based vertex detector were used to reconstruct B-decay vertices with high efficiency and purity, and to provide precise measurements of the kinematic quantities used in this technique. We measured the B energy with good efficiency and resolution over the full kinematic range. We compared the scaled B-hadron energy distribution with models of b-quark fragmentation and with several ad hoc functional forms. A number of models and functions are excluded by the data. The average scaled energy of weakly decaying B hadrons was measured to be (xb) = 0.709±0.003(stat)±0.003(syst)±0.002(model).

Abstract:

The improved direct measurement of Ab at the Z⁰ pole using a lepton tag was presented. The measurements were carried out using identified charged leptons from semileptonic decays. The results obtained were found to be in agreement with the standard model predictions and were insensitive to uncertainties in standard model parameters and the top quark and Higgs boson masses.

Abstract:

The structure of 3-jet e⁺ e^- → bb̄g events has been studied using hadronic Z⁰ decays recorded in the SLC Large Detector experiment at SLAC. Three-jet final states were selected and the charge-coupled-device-based vertex detector was used to identify two of the jets as b or b̄; the remaining jet in each event was tagged as the gluon jet. Distributions of the gluon energy and polar angle with respect to the electron beam were measured over the full kinematic range, and used to test the predictions of perturbative QCD. We find that beyond-leading-order QCD calculations are needed to reproduce the features seen in the data. The energy distribution is sensitive to an anomalous b chromomagnetic moment K at the bb̄g vertex. We measured κ to be consistent with zero and set 95% confidence level limits on its value, -0.06<κ<0.04. © 2002 The American Physical Society.