A measurement of the forward-backward asymmetry of and at centre of mass energies on and near theZ0 peak usingD*± mesons

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 theZ0 into charm and bottom quarks are identified using 6507 chargedD* mesons, reconstructed in the decaysD*±→D0π±→(K∓π±)π±,D*±→D0π±→(K∓π±π0)π± andD*±→D0π±→(K∓π±π∓π±)π±. Thec quark asymmetry on theZ0 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 theZ0 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.