Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Penguin Zoology in $B\to\pi\pi$ and the Extraction of the CKM Angle
  $\alpha$   We reanalyze the decay $B_d\to\pi^+\pi^-$ without assuming dominance of QCD
penguins with internal top-quark exchanges. In that case the weak phase of the
$\bar b \to\bar d$ QCD penguin amplitude is not related in a simple way to the
CKM angle $\beta$. Nevertheless it is still possible to extract the CKM angle
$\alpha$ in a transparent and almost model-independent way from the
time-dependent CP-violating asymmetry of the transition $B_d\to\pi^+\pi^-$.
Aside from that CP asymmetry this approach needs as an input only amplitudes of
decays with branching ratios of order $10^{-5}$ and will thus be well within
reach at future $B$-factories.

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The categories of this paper are: nlin
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The categories of this paper are: adap-org
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The categories of this paper are: funct-an
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The categories of this paper are: dg-ga
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The categories of this paper are: mtrl-th
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The categories of this paper are: chem-ph
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The categories of this paper are: solv-int
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The categories of this paper are: nucl-th
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The categories of this paper are: plasm-ph
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The categories of this paper are: math-ph
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The categories of this paper are: math
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The categories of this paper are: eess
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The categories of this paper are: q-bio
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The categories of this paper are: physics
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The categories of this paper are: gr-qc
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The categories of this paper are: stat