Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Measurement of the branching fraction for the decay B^0 --> D^{*+}D^{*-}   Decays of the type B --> D^{(*)} anti-D^{(*)} can be used to provide a
measurement of the parameter sin2beta of the Unitarity Triangle that is
complementary to the measurement derived from the mode B^0 --> J/psi K_s^0. In
this document we report a measurement of the branching fraction for the decay
B^0 --> D^{*+}D^{*-} with the BABAR detector. With data corresponding to an
integrated luminosity of 20.7 fb^{-1} collected at the Upsilon(4S) resonance
during 1999-2000, we have reconstructed 38 candidate signal events in the mode
B^0 --> D^{*+}D^{*-} with an estimated background of 6.2+/-0.5 events. From
these events, we determine the branching fraction to be BF(B^0 -->
D^{*+}D^{*-}) = (8.0+/-1.6(stat)+/-1.2(syst))x10^{-4} (preliminary).

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The categories of this paper are: gr-qc
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The categories of this paper are: funct-an
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The categories of this paper are: cond-mat
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The categories of this paper are: ao-sci
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The categories of this paper are: bayes-an
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The categories of this paper are: chao-dyn
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The categories of this paper are: nucl-th
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The categories of this paper are: adap-org
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The categories of this paper are: hep-th
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The categories of this paper are: quant-ph
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The categories of this paper are: plasm-ph
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The categories of this paper are: q-bio
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The categories of this paper are: q-fin
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The categories of this paper are: math
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The categories of this paper are: chem-ph
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The categories of this paper are: math-ph