Measurement of the forward backward asymmetry of c and b quarks at the Z pole using reconstructed D mesons

A measurement of the forward-backward asymmetry of e+e-→c anti c and e+e-→b anti b on the Z resonance is performed using about 3.5 million hadronic Z decays collected by the DELPHI detector at LEP in the years 1992 to 1995. The heavy quark is tagged by the exclusive reconstruction of several D meson decay modes. The forward-backward asymmetries for c and b quarks at the Z resonance are determined to be: AFBc(√(s)=91.235/ GeV)=0.0659±0.0094(stat)±0.035(syst), AFBb(√(s)=91.235 GeV)=0.0762±0.0194(stat)±0. 0085(syst), AFBc(√(s)=89.434 GeV)=-0.0496±0.0368(stat) pm0.0053(syst), AFBb(√(s)=89.434 GeV)=0.0567±0.0756(stat)±0.0117(syst), AFBc(√(s)=92.990 GeV)=0.1180±0. 0318(stat)±0.0062(syst), AFBb(√(s)=92.990 GeV)=0.082±0. 0633(stat)±0.0122(syst). The combination of these results leads to an effective electroweak mixing angle of sin2θefflept=0. 2332±0.0016. (orig.)