D. Buskulic et al., A MEASURE VERTICAL-BAR-V-CB-VERTICAL-BAR FROM (B)OVER-BAR(0)-]D-ASTERISK-(NU)OVER-BAR(L)(L), Physics letters. Section B, 359(1-2), 1995, pp. 236-248
From approximately 3 million hadronic decays of Z bosons recorded with
the ALEPH detector at LEP, a sample of 410 +/- 32 ($) over bar B-0 --
> D(+)l(-)nu(l) candidates is selected, where l is either an electron
or a muon. The differential decay rate d Gamma(($) over bar B-0 --> D
(+)l(-)nu(l))/d omega from this sample is fitted, yielding a value fo
r the product of the CKM matrix element \V-cb\ and the normalisation o
f the decay form factor at the point of zero recoil of the D(+) meson
F(omega = 1)\V-cb\ = (31.4 +/- 2.3(stat) +/- 2.5(syst)) x 10(-3). A v
alue for \V-cb\ is extracted using theoretical calculations of the for
m factor normalisation, with the result \V-cb\ = (34.5 +/- 2.5(stat) /- 2.7(syst) +/- 1.5(theory)) X 10(-3) From the integrated spectrum, t
he measured branching fraction is Br(($) over bar B-0 --> D(+)l(-)nu)
= (5.18 +/- 0.30(stat) +/- 0.62(syst))%.