Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Exact Solutions in Five-Dimensional Axi-dilaton Gravity with
  Euler-Poincare Term   We examine the effective field equations that are obtained from the
axi-dilaton gravity action with a second order Euler-Poincare term and a
cosmological constant in all higher dimensions. We solve these equations for
five-dimensional spacetimes possessing homogeneity and isotropy in their
three-dimensional subspaces. For a number of interesting special cases we show
that the solutions fall into two main classes: The first class consists of
time-dependent solutions with spherical or hyperboloidal symmetry which require
certain fine-tuning relations between the coupling constants of the model and
the cosmological constant. Solutions in the second class are locally static and
prove the validity of Birkhoff's staticity theorem in the axi-dilaton gravity.
We also give a special class of static solutions, among them the well-known
black hole solutions in which the usual electric charge is superseded by an
axion charge.

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The categories of this paper are: nlin
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The categories of this paper are: astro-ph
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The categories of this paper are: econ
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The categories of this paper are: stat
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The categories of this paper are: quant-ph
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The categories of this paper are: mtrl-th
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The categories of this paper are: ao-sci
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The categories of this paper are: hep-ph
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The categories of this paper are: funct-an
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The categories of this paper are: q-bio
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The categories of this paper are: solv-int
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The categories of this paper are: eess
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The categories of this paper are: physics
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The categories of this paper are: cs
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The categories of this paper are: hep-lat
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The categories of this paper are: nucl-th