Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: NNLO QCD corrections to the polarized top quark decay $t(\uparrow) \to
  X_b+W^+$   We compute the next-to-next-to-leading order (NNLO) QCD corrections to the
decay $t(\uparrow) \to X_b +W^+$ of a polarized top quark. The spin-momentum
correlation in this quasi two-body decay is described by the polar angle
distribution $\mathrm{d}\Gamma/\mathrm{d}\cos\theta_P=\frac{\Gamma}{2}(1+P_t\,
\alpha_P\, \cos\theta_P)$ where $P_t$ is the polarization of the top quark and
$\alpha_P$ denotes the asymmetry parameter of the decay. For the latter we find
$\alpha^{\mathrm{NNLO}}_P=0.3792\pm 0.0037$.

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The categories of this paper are: acc-phys
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The categories of this paper are: cmp-lg
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The categories of this paper are: nlin
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The categories of this paper are: chao-dyn
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The categories of this paper are: stat
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The categories of this paper are: dg-ga
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The categories of this paper are: astro-ph
3
The categories of this paper are: physics
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The categories of this paper are: atom-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: q-fin
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The categories of this paper are: adap-org
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The categories of this paper are: solv-int
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The categories of this paper are: cs
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The categories of this paper are: bayes-an
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The categories of this paper are: econ