2 research outputs found
A Measurement of A(b)(FB) in lifetime tagged heavy flavor Z decays
A new measurement of the forward-backward asymmetry in Z -> b bbar decays is presented. Hadrons from b decays are tagged using their long lifetimes. The b quark charge and direction are reconstructed with a hemisphere charge algorithm. The asymmetry and reconstructed b hemisphere charge are measured in the 69 pb(-1) of data collected by ALEPH during 1991, 1992 and 1993. They are used to extract sin^2(theta(w)eff), which is determined to be 0.2315 +/- 0.0016 (stat.) +/- 0.0009 (syst.), corresponding to an A(FB)b of 0.00992 +/- 0.0084 (stat.) +/- 0.0046 (stat.)
One prong tau decays into charged kaons
Form a sample of about 75000 τ decays measured in the ALEPH detector, 1-prong charged kaon decays are identified by the dE/dx measurement in the central detector. The resulting branching ratios for the inclusive and exclusive modes are: B(τ → ντK− ≥ 0π0 ≥ 0K0) = (1.60±0.07±0.12)%, B(τ → ντK− = (0.64±0.05±0.05)%, B(τ → ντ−π0 = (0.53±0.05±0.07)% and B(τ → ντK−π0π0) = (0.04±0.03±0.02)%. Exclusive modes are corrected for measured KL0 production. The rate for τ → ντK− agrees well with the prediction based on τ - μ universality