First Measurement of the Double-inclusive $B/\overline{B}$ Hadron Energy Distribution in e+e– Annihilations, and of Angle-Dependent Moments of the B and $\overline{B}$

Abstract

We have made the first measurement of the double-inclusive B/ $\overline{B}$ 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/ $\overline{B}$ -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/ $\overline{B}$ energies with good efficiency and resolution over the full kinematic range. We measured moments of the scaled energies of the B and $\overline{B}$ 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.