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Heister, A.; Schael, S.; Barate, R.; de Bonis, I.; Decamp, D.; Goy, C.; Lees, J P.; Merle, E.; Minard, M N.; Pietrzyk, B.; Boix, G.; Bravo, S.; Chmeissani, M.; Crespo, J M.; Fernandez, E.; Fernandez-Bosman, M.; Garrido, L.; Grauges, E.; Martinez, M.; Merino, G.; Miquel, R.; Mir, L M.; Pacheco, A.; Ruiz, H.; Colaleo, A.; Creanza, D.; de Palma, M.; Iaselli, G.; Maggi, G.; Maggi, M.; Nuzzo, S.; Ranieri, A.; Raso, G.; Ruggieri, F.; Silvestris, L.; Tempesta, P.; Tricomi, A.; Zito, G.; Huang, X.; Lin, Jiali; Ouyang, Q.; Wang, T.; Xie, Y.; Xu, R.; Xue, S.; Zhang, J.; Zhang, L.; Zhao, W.; Abbaneo, D.; Azzurri, P.; Buchmuller, O.; Cattaneo, M.; Cerutti, F.; Clerbaux, B.; Drevermann, H.; Forty, R W.; Frank, M.; Gianotti, F.; Greening, T C.; Hansen, J B.; Harvey, J.; Hutchcroft, D E.; Janot, P.; Jost, B.; Kado, M.; Mato, P.; Moutoussi, A.; Ranjard, F.; Rolandi, L.; Schlatter, D.; Schneider, O.; Sguazzoni, G.; Tejessy, W.; Teubert, F.; Valassi, A.; Videau, I.; Ward, J.; Badaud, F.; Falvard, Alain; Gay, Pascal; Henrard, Pierre; Jousset, J.; Michel, B.; Monteil, S.; Montret, Jean-Claude; Pallin, D.; Perret, Pascal; Hansen, J D.; Hansen, J R.; Hansen, P H.; Nilsson, B S.; Waananen, A.; Kyriakis, A.; Markou, C.; Simopoulou, E.; Vayaki, A.; Zachariadou, K.; Blondel, A.; Bonneaud, G.; Brient, J C.
The European physical journal. C, Particles and fields, 2002, Letnik: 24Journal Article
The sample of hadronic Z decays collected by the ALEPH detector at LEP in the years 1991-1995 is analysed in order to measure the forward-backward asymmetry in $Z \to b\bar{b}$ and $Z \to c\bar{c}$ events and the $B^0-\bar{B^0}$ average mixing parameter $\bar{\chi}$. Quark charges are tagged by the charges of electrons and muons produced in b and c semileptonic decays. Multivariate analyses are used to separate the event flavours and $b \to \ell$/$b \to c \to ell$ processes. The b and c quark asymmetries are measured simultaneously; the average mixing parameter and the pole asymmetries are determined to be \begin{eqnarray*} \bar{\chi} &=& 0.1196 \pm 0.0049 (stat) {}^{+0.0043}_{-0.0050} (syst) \\ \A^{0,b}_{FB} &=& 0.0998 \pm 0.0040 (stat) \pm 0.0017 (syst),\\ \A^{0.c}_{FB} &=& 0.0732 \pm 0.0053 (stat) \pm 0.0037 (syst).\\ \end{eqnarray*} These asymmetries, combined with the ALEPH measurements of the b asymmetry using inclusive b hadron decays and of the c asymmetry using reconstructed D mesons, correspond to a value of the effective electroweak mixing angle of $\sin^2\theta^{eff}_{W} = 0.23188 \pm 0.00046$.
