Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Mixing-Induced CP Violation in the Decay $B_d\to K^0 \bar K^0$ within
  the Standard Model   Recently, flavour $SU(3)$ symmetry of strong interactions has been combined
with certain dynamical assumptions to derive triangle relations among $B$-meson
decay-amplitudes. We show that these relations allow a prediction of the
mixing-induced CP asymmetry $\acpmi(B_d\to K^0\bar K^0)$. Contrary to
statements made in several previous papers, this asymmetry should be
non-vanishing in the Standard Model due to QCD-penguins with internal up- and
charm-quark exchanges and could be as large as $\order(30\%)$. The branching
ratio BR$(B_d\to K^0\bar K^0)$ is expected to be of $\order(10^{-6})$. In the
future, the results presented in this letter should allow interesting tests of
the $SU(3)$ triangle relations and of the Standard Model description of CP
violation.

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The categories of this paper are: eess
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The categories of this paper are: acc-phys
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The categories of this paper are: q-fin
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The categories of this paper are: dg-ga
5
The categories of this paper are: gr-qc
32
The categories of this paper are: atom-ph
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The categories of this paper are: chem-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: nlin
13
The categories of this paper are: quant-ph
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The categories of this paper are: funct-an
6
The categories of this paper are: astro-ph
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The categories of this paper are: nucl-ex
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The categories of this paper are: stat
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The categories of this paper are: hep-th
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The categories of this paper are: nucl-th