D. Buskulic et al., MEASUREMENT OF THE EFFECTIVE B-QUARK FRAGMENTATION FUNCTION AT THE Z-RESONANCE, Physics letters. Section B, 357(4), 1995, pp. 699-714
Using a sample of about 1.46 million hadronic Z decays collected betwe
en 1991 and 1993 with the ALEPH detector at LEP, the energy distributi
on of the B-0 and B-+/- mesons produced at the Z resonance is measured
by reconstructing semileptonic decays B --> l nu(l)D(X) or B --> l nu
(l)D(+)(X). The charmed mesons are reconstructed through the decay mo
des D-0 --> K(-)pi(+), D-0, --> K(-)pi(+)pi(-)pi(+),D+ --> K(-)pi(+)pi
(+), and D(+) --> D-0 pi(+). The neutrino energy is estimated from th
e missing energy in the lepton hemisphere. Accounting for B and B** p
roduction, the shape of the scaled energy distribution x(E)((b)) for m
esons containing a b quark is compared to the predictions of different
fragmentation models. The mean value of x(E)((b)) is found to be [x(E
)((b))] = 0.715 +/- 0.007(stat) +/- 0.013(syst).