Measurement of the<i>bb¯</i>fraction in hadronic<i>Z</i>decays

Abstract

Using isolated leptons reconstructed in the Mark II detector to tag bb\ifmmode\bar\else\textasciimacron\fi{} events, we measure the fraction of bb\ifmmode\bar\else\textasciimacron\fi{} events in hadronic ${\mathit{Z}}^{0}$ decays to be 0.${23}_{\mathrm{\ensuremath{-}}0.09}^{+0.11}$, in good agreement with the standard-model prediction of 0.22. We find \ensuremath{\Gamma}(Z\ensuremath{\rightarrow}bb\ifmmode\bar\else\textasciimacron\fi{})=0.${43}_{\mathrm{\ensuremath{-}}0.17}^{+0.21}$ GeV.