| Abstract |
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We determine the relative branching fractions
of semileptonic B decays to charmed final states. The measurement is
performed on the recoil from a fully reconstructed B meson in a sample of
362 million BBbar pairs collected at the Upsilon(4S) resonance
with the BaBar detector. A simultaneous fit to a set of discriminating
variables is performed on a
sample of Bbar --> D X l^- anti-nu_l decays
to determine the contributions from the different channels.
We measure Gamma(B- --> D l^- anti-nu_l)/Gamma
(B- --> D X l^- anti-nu_l)= 0.227 +/- 0.014 +/- 0.016,
Gamma(B- --> D* l^- anti-nu_l)/Gamma (B- -->
D X l^- anti-nu_l)= 0.582 +/- 0.018 +/- 0.030 and Gamma(B-
--> D** l^- anti-nu_l)/Gamma (B- --> D X l^-
anti-nu_l)= 0.191 +/- 0.013 +/- 0.019 for the charged B sample,
and Gamma(B0bar --> D l^- anti-nu_l)/Gamma
(B0bar --> D X l^- anti-nu_l)= 0.215 +/- 0.016
+/- 0.013, Gamma(B0bar --> D* l^-
anti-nu_l)/Gamma (B0bar --> D X l^-
anti-nu_l)= 0.537 +/- 0.031 +/- 0.036 and Gamma(B0bar
--> D** l^- anti-nu_l)/Gamma (B0bar
--> D X l^- anti-nu_l)= 0.248 +/- 0.032 +/- 0.030
for the neutral B sample, where uncertainties are statistical and
systematic, respectively.
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