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 (c) over bar and e(+)e(-) --> b (b) over bar 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: A(FB)(c)(root s = 91.235 GeV) = 0.0659 +/- 0.0094(stat) +/- 0.0035(syst) A(FB)(b)(root s = 91.235 GeV) = 0.0762 +/- 0.0194(stat) +/- 0.0085(syst) A(FB)(c)(root s = 89.434GeV) = -0.0496 +/- 0.0368(stat) +/- 0.0053(syst) A(FB)(b)(root s = 89.434 GeV) = 0.0567 +/- 0.0756(stat) +/- 0.0117(syst) A(FB)(c)(root s = 92.990 GeV) = 0.1180 +/- 0.0318(stat) +/- 0.0062(syst) A(FB)(b)(root s = 92.990 GeV) = 0.0882 +/- 0.0633(stat) +/- 0.0122(syst) The combination of these results leads to an effective electroweak mixing angle of: sin(2) theta(eff)(lept) = 0.2332 +/- 0.0016. RI De Angelis, Alessandro/B-5372-2009; Gonzalez Caballero, Isidro/E-7354-2010; Krammer, Manfred/A-6508-2010; Muresan, Raluca-Anca/C-3725-2011; Katsanevas, Stavros/A-4297-2011; Marti-Garcia, Salvador/F-3085-2011; Verzi, Valerio/B-1149-2012; branchini, paolo/A-4857-2011; Shellard, Ronald/G-4825-2012; Petrolini, Alessandro/H-3782-2011; Fruhwirth, Rudolf/H-2529-2012; Monge, Maria Roberta/G-9127-2012