Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Exclusive Decay of $1^{--}$ Quarkonia and $B_c$ Meson into a Lepton Pair
  Combined with Two Pions   We study the exclusive decay of $J/\Psi$, $\Upsilon$ and $B_c$ into a lepton
pair combined with two pions in the two kinematic regions. One is specified by
the two pions having large momenta, but a small invariant mass. The other is
specified by the two pions having small momenta. In both cases we find that in
the heavy quark limit the decay amplitude takes a factorized form, in which the
nonperturbative effect related to heavy meson is represented by a NRQCD matrix
element. The nonperturbative effects related to the two pions are represented
by some universal functions characterizing the conversion of gluons into the
pions. Using models for these universal functions and chiral perturbative
theory we are able to obtain numerical predictions for the decay widths. Our
numerical results show that the decay of $\jpsi$ is at order of $10^{-5}$ with
reasonable cuts and can be observed at BES II and the proposed BES III and
CLEO-C. For other decays the branching ratio may be too small to be measured.

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The categories of this paper are: nucl-ex
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The categories of this paper are: solv-int
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The categories of this paper are: cmp-lg
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The categories of this paper are: stat
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The categories of this paper are: physics
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The categories of this paper are: chao-dyn
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The categories of this paper are: hep-th
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The categories of this paper are: funct-an
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The categories of this paper are: atom-ph
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The categories of this paper are: q-bio
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The categories of this paper are: econ
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The categories of this paper are: bayes-an
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The categories of this paper are: hep-ex
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The categories of this paper are: hep-lat
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The categories of this paper are: plasm-ph
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The categories of this paper are: chem-ph