Measurement of the b forward-backward asymmetry and mixing using high-p⊥ leptons

Abstract The B 0 - B 0 average mixing parameter χ and b forward-backward asymmetry A FB 0 (b) are measured from a sample of about 4 200 000 Z → qq events recorded with the ALEPH detector at LEP in the years 1990–1995. High transverse momentum electrons and muons produced in b semileptonic decays provide the tag of the quark flavour and of its charge. The average mixing parameter and the pole b asymmetry are measured to be χ = 0.1246 ± 0.0051 stat ± 0.0052 syst , A FB 0 (b) = 0.1008 ± 0.0043 stat ± 0.0028 syst . The value of sin 2 θ w eff = 0.23198 ± 0.00092 is extracted from the asymmetry measurement.