Measurement of the B00 mixing parameter and the Z → b forward-backward asymmetry

We have measured the time integrated B0 B 0 mixing parameter and the forward-backward asymmetry in the process e+e− → b b using hadronic events containing muons or electrons. The data sample corresponds to 1,044,000 hadronic decays of the Z. From a fit to the momentum and transverse momentum distributions for single lepton and dilepton events, we have determined the B0 B 0 mixing parameter to be χB = 0.123 ± 0.012 (stat.) ± 0.008 (sys.), and the b b forward-backward asymmetry at the effective center-of-mass energy √s = 91.30 GeV to be A b b = 0.087 ± 0.011 ( stat. ) ± 0.004 ( sys. ) This measurement corresponds to a value of the effective electroweak mixing angle of sin 2 θ w = 0.2335 ± 0.0021 .