Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Uniqueness theorem for stationary black ring solution of $\sigma$-models
  in five dimensions   We study axisymmetric self-gravitating non-linear $\sigma$-model in
five-dimensional spacetime admitting three commutating Killing vector fields.
We show that the only asymptotically flat black ring solution with a regular
event horizon is the black ring characterized by mass and two angular momenta
with constant mapping.

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The categories of this paper are: physics
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The categories of this paper are: astro-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: chem-ph
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The categories of this paper are: quant-ph
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The categories of this paper are: nucl-th
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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: hep-lat
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The categories of this paper are: funct-an
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The categories of this paper are: q-alg
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The categories of this paper are: acc-phys
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The categories of this paper are: mtrl-th
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The categories of this paper are: supr-con
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The categories of this paper are: nlin
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The categories of this paper are: hep-ex