G. Abbiendi et al., Measurement of the semileptonic branching ratio of charm hadrons produced in Z(0) -> c(c)over-bar decays, EUR PHY J C, 8(4), 1999, pp. 573-584
The inclusive charm hadron semileptonic branching fractions B(c --> e) and
B(c --> mu) in Z(0) --> c (c) over bar events have been determined using 4.
4 million hadronic Z(0) decays collected with the OPAL detector at LEP. A c
harm-enriched sample is obtained by. selecting events with reconstructed D*
(+/-) mesons. Using leptons found in the hemisphere opposite that of the D*
(+/-) mesons, the semileptonic branching fractions of charm hadrons are mea
sured to be
B(c --> e) = 0.103 +/- 0.009(-0.008)(+0.009) and B(c --> mu) = 0.090 +/ 0.0
07(-0.006)(+0.007),
where the first errors are in each case statistical and the second systemat
ic. Combining these measurements, an inclusive semileptonic branching fract
ion of charm hadrons of
B(c --> l) = 0.095 +/- 0.006(-0.006)(+0.007)
is obtained.