Improved measurement of the probability for gluon splitting into bb̄ in Z0 decays

We have measured gluon splitting into bottom quarks, g→bb̄, in hadronic Z0 decays collected by SLD between 1996 and 1998. The analysis was performed by looking for secondary bottom production in 4-jet events of any primary flavor. 4-jet events were identified, and in each event a topological vertex-mass technique was applied to the two jets closest in angle in order to identify them as b or b̄ jets. The upgraded CCD-based vertex detector gives very high B-tagging efficiency, especially for B hadrons with the low energies typical of this process. We measured the rate of g→bb̄ production per hadronic event, gbb̄, to be (2.44±0.59(stat.)±0.34(syst.))×10−3.