Multilepton final states and the weak interactions of the fifth quark

Abstract

We summarize the evidence for the properties of a fifth quark, denoted as $b$, which is a constituent of $\Upsilon (9.4\mathrm{} \mathrm{GeV}/c^2)$. We show how an analysis of the lepton content of final states arising from unbound ($b\overline{b}$) production can yield the relative strengths of the $b\to u+W^{-}$ and $b\to c+W^{-}$ weak-current transitions.