D. Buskulic et al., MEASUREMENT OF THE RATIO GAMMA-B(B)BAR GAMMA HAD USING EVENT SHAPE VARIABLES/, Physics letters. Section B, 313(3-4), 1993, pp. 549-563
The branching fraction of Z --> bbBAR relative to all hadronic decays
of the Z has been measured using event shape variables to preferential
ly select Z --> bbBAR events. The method chosen applies a combination
of shape discriminators and the selection of high transverse momentum
leptons to event hemispheres. From a sample of 440000 hadronic Z decay
s collected with the ALEPH detector at LEP, the ratio GAMMA(bbBAR)/GAM
MA(had) = 0.228+/-0.005(stat.)+/-0.005(syst.) is measured.