A measurement of the forward-backward asymmetry of \(e^ + e^ - \to c\bar c\) and \(e^ + e^ - \to b\bar b\) at centre of mass energies on and near theZ 0 peak usingD *± mesons

Abstract A measurement is presented of the forwardbackward asymmetry of the processes\(e^ + e^ + \to c\bar c\) and\(e^ + e^ + \to b\bar b\) at centre of mass energies near 91 GeV. Decays of theZ 0 into charm and bottom quarks are identified using 6507 chargedD * mesons, reconstructed in the decaysD *±→D 0 π ±→(K ∓ π ±)π ±,D *±→D 0 π ±→(K ∓ π ± π 0)π ± andD *±→D 0 π ±→(K ∓ π ± π ∓ π ±)π ±. Thec quark asymmetry on theZ 0 peak is measured to be $$A_{FB}^c = 0.052 \pm 0.028(stat.) \pm 0.012(sys.).$$ The energy dependence of the asymmetry has been investigated at energies close to theZ 0 peak. Consistency with the predictions of the Standard Model is found. Combining these measurements with the determination of the asymmetries from semileptonic decays, the following results forb andc quarks are found $$\begin{gathered} A_{FB}^c = 0.032 \pm 0.021(stat.) \pm 0.015(sys.), \hfill \\ A_{FB}^b = 0.096 \pm 0.017(stat.) \pm 0.008(sys.), \hfill \\ \end{gathered} $$ with a correlation coefficient of +0.15.