First study of the structure of e+e- -> b bbar g events and limits on the anomalous chromomagnetic moment of the b-quark

TL;DR

This study analyzed e+e- -> b bbar g events from Z0 decays, measuring gluon distributions and setting the first limits on the b-quark's anomalous chromomagnetic moment, consistent with zero.

Contribution

It provides the first measurements of gluon energy and angle distributions in b-quark events and sets new limits on the b-quark's anomalous chromomagnetic moment.

Findings

Gluon energy and angle distributions match perturbative QCD predictions.

Measured the b-quark's anomalous chromomagnetic moment to be within -0.17 and 0.11.

First limits established on the b-quark's chromomagnetic moment.

Abstract

The structure of e+e- -> b bbar g events was studied using Z0 decays recorded in the SLD experiment at SLAC. Three-jet final states were selected and the CCD-based vertex detector was used to identify two of the jets as b or bbar. Distributions of the gluon energy and polar angle were measured over the full kinematic range for the first time, and compared with perturbative QCD predictions. The energy distribution is potentially sensitive to an anomalous b chromomagnetic moment kappa. We measured kappa to be consistent with zero and set the first limits on its value, -0.17 < kappa < 0.11 at 95% c.l.