Measurement of the asymmetry ofb quark production ine + e − annihilation at $$\sqrt s = 35 GeV$$

The forward-backward asymmetry in the reaction e+e-→bb has been determined at centre of mass energies near 35 GeV using the TASSO detector. We report results from three different methods. The combined result of the measurements is\(\overline A _b = - 0.21 \pm 0.08\) ignoring\(B^0 \bar B^0 \) mixing. Taking mixing into account leads to a corrected asymmetry of\(\overline {A_b^{cor} } = - 0.28 \pm 0.11\). The axial vector coupling constant of theb quark as calculated from the corrected asymmetry isab=−1.2±0.5 to be compared with the valuea b SM =−1 from the standard model.