Measurement of the forward-backward asymmetry of charm and bottom quarks at the Z pole using D*+- mesons

The forward-backward asymmetries for the processes\(e^ + e^ - \to c\bar c\) and\(e^ + e^ - \to b\bar b\) at theZ resonance are measured using identifiedD*± mesons. In 905,000 selected hadronic events, taken in 1991 and 1992 with the DEL-PHI detector at LEP, 4757D*+→D0π+ decays are reconstructed. Thec andb quark forward-backward asymmetries are determined to be: $$\begin{gathered} A_{FB}^{c\bar c} = 0.077 \pm 0.029(stat) \pm 0.012(sys), \hfill \\ A_{FB}^{b\bar b} = 0.059 \pm 0.062(stat) \pm 0.024(sys). \hfill \\ \end{gathered} $$ Constraining theb asymmetry to the value measured by DELPHI using independent analyses, the charm asymmetry is determined to be: $$A_{FB}^{c,const} = 0.068 \pm 0.027(stat) \pm 0.011(sys).$$ . This result corresponds to an effective electroweak mixing angle measured using charm quark events of: $$\sin ^2 \theta _{eff}^{lept} = 0.2307 \pm 0.0062(stat) \pm 0.0026(sys).$$