Measurement of $$R_\mathrm{b}$$ and $$\mathrm{Br}(\mathrm{b} \rightarrow \ell\nu\mathrm{X})$$ at LEP using double-tag methods

Abstract. We present a combined measurement of $$R_\mathrm{b} = \Gamma(\mathrm{Z \rightarrow b\bar{b}}) / \Gamma(\mathrm{Z}\rightarrow \mbox{hadrons})$$ and the semileptonic branching ratio of b quarks in Z decays, $$\mathrm{Br}(\mathrm{b} \rightarrow \ell\nu\mathrm{X})$$, using double-tag methods. Two analyses are performed on one million hadronic Z decays collected in 1994 and 1995. The first analysis exploits the capabilities of the silicon …