Philip Burrows

Abstract:

A search for B0s-B0s oscillations is performed using a sample of 400 000 hadronic Z0 decays collected by the SLAC Large Detector experiment. The B0s candidates are reconstructed in the B0s→D-sX channel with D-s→Ππ-, K*0K-. The B0s production flavor is determined using the large forward-backward asymmetry of polarized Z0→bb decays and charge information in the hemisphere opposite that of the B0s candidate. The decay flavor is tagged by the charge of the D±s. From a sample of 361 candidates with an average B0s purity of 40%, we exclude the following values of the oscillation frequency: Δms<1.4 ps-1 and 2.4<Δms <5.3 ps-1 at the 95% confidence level.

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.