Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Measurement of the B0 Lifetime with Partially Reconstructed B0 --> D*-
  l+ nu Decays   The B0 lifetime has been measured with a sample of 23 million BBbar pairs
collected by the BaBar detector at the PEP-II e+e- storage ring during 1999 and
2000. Events from the semileptonic decay B0 --> D*- l+ nu have been selected
with a partial reconstruction method in which only the charged lepton and the
slow pion from the D*- --> D0bar pi- decay are reconstructed. The result is
tau_B0 = 1.529+/-0.012 (stat) +/- 0.029 (syst) ps.

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The categories of this paper are: atom-ph
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The categories of this paper are: adap-org
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The categories of this paper are: physics
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The categories of this paper are: nucl-th
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The categories of this paper are: math
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The categories of this paper are: q-alg
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The categories of this paper are: nucl-ex
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The categories of this paper are: chao-dyn
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The categories of this paper are: q-bio
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The categories of this paper are: astro-ph
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The categories of this paper are: gr-qc
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The categories of this paper are: hep-lat
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The categories of this paper are: ao-sci
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The categories of this paper are: hep-th
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The categories of this paper are: nlin
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The categories of this paper are: bayes-an