Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Measurement of the Branching Fraction of e^+e^- --> B0B0bar at the
  Upsilon(4S) Resonance   We report a measurement of the branching fraction e^+e^- --> B0B0bar with a
data sample of 81.7 fb^-1 collected at the Upsilon(4S) resonance with the BABAR
detector at the PEP-II asymmetric-energy e^+e^- storage ring. Using partial
reconstruction of the decay B0bar --> D^{*+} \ell^{-} \bar{\nu}_{\ell} we
obtain a preliminary result of f00 = 0.486 +- 0.010(stat.) +- 0.009(sys.). Our
result does not depend on branching fractions of the B0bar and the D^{*+} decay
chains, on the simulated reconstruction efficiency, on the ratio of the charged
and neutral B meson lifetimes, nor on assumption of isospin symmetry. This
measurement is important for normalizing many B decay branching fractions, and
contributes to our understanding of isospin violation in the Upsilon(4S)
system.

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The categories of this paper are: hep-ph
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The categories of this paper are: ao-sci
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The categories of this paper are: math
37
The categories of this paper are: supr-con
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The categories of this paper are: mtrl-th
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The categories of this paper are: hep-th
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The categories of this paper are: acc-phys
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The categories of this paper are: econ
13
The categories of this paper are: quant-ph
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The categories of this paper are: cond-mat
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The categories of this paper are: q-fin
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The categories of this paper are: solv-int
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The categories of this paper are: q-alg
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The categories of this paper are: physics
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The categories of this paper are: comp-gas
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The categories of this paper are: nucl-th