First measurement of the double-inclusive B/Bbar hadron energy distribution in e+e- annihilations, and of angle-dependent moments of the B and Bbar energies

TL;DR

This paper presents the first measurement of the joint energy distribution of B and Bbar hadrons in electron-positron collisions, using advanced vertex detection to test QCD predictions and factorization in heavy-quark production.

Contribution

It introduces a novel technique for measuring B/Bbar energies and moments in e+e- annihilations, providing new data to test perturbative QCD and factorization assumptions.

Findings

Measured B/Bbar energy distributions with high accuracy.

Found that NLO QCD calculations agree with the data.

Provided insights into heavy-quark production mechanisms.

Abstract

We have made the first measurement of the double-inclusive B/Bbar 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/Bbar decay vertices with high efficiency and purity, and to provide measurements of the kinematic quantities used to calculate the B energies in this novel technique. We measured the B/Bbar energies with good efficiency and resolution over the full kinematic range. We measured moments of the scaled energies of the B and Bbar 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.