P. Abreu et al., Measurement of the forward backward asymmetry of c and b quarks at the Z pole using reconstructed D mesons, EUR PHY J C, 10(2), 1999, pp. 219-237
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 a
bout 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 recon
struction 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 a
ngle of:
sin(2) theta(eff)(lept) = 0.2332 +/- 0.0016.