QCD tests using bb̄g events and a new measurement of the B-hadron energy spectrum

Abstract

We present new studies of 3-jet final states from hadronic Z 0 decays recorded by the SLD experiment, in which jets are identified as quark, antiquark or gluon. Our gluon energy spectrum, measured over the full kinematic range, is consistent with the predictions of QCD, and we derive a limit on an anomalous chromomagetic bbg coupling. We measure the parity violation in Z 0 decays into bb̄g to be consistent with the predictions of electroweak theory and QCD, and perform new tests of T- and CP-conservation at the bbg vertex. We also present a new technique for reconstructing the energy of a B hadron using the set of charged tracks attached to a secondary vertex. The B hadron energy spectrum is measured over the full kinematic range, allowing improved tests of predictions for the shape of the spectrum. The average scaled energy is measured to be 〈 χ B 〉 = 0.719 ± 0.005( stat.) (Preliminary).