Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Second-order Gauge Invariant Cosmological Perturbation Theory: --
  Einstein equations in terms of gauge invariant variables --   Along the general framework of the gauge invariant perturbation theory
developed in the papers [K. Nakamura, Prog. Theor. Phys. {\bf 110} (2003), 723;
{\it ibid}, {\bf 113} (2005), 481.], we formulate the second order gauge
invariant cosmological perturbation theory in a four dimensional homogeneous
isotropic universe. We consider the perturbations both in the universe
dominated by the single perfect fluid and in that dominated by the single
scalar field. We derive the all components of the Einstein equations in the
case where the first order vector and tensor modes are negligible. All
equations are derived in terms of gauge invariant variables without any gauge
fixing. These equations imply that the second order vector and tensor modes may
be generated due to the mode-mode coupling of the linear order scalar
perturbations. We also briefly discuss the main progress of this work by the
comparison with some literatures.

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The categories of this paper are: hep-lat
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The categories of this paper are: nucl-th
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The categories of this paper are: cond-mat
16
The categories of this paper are: stat
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The categories of this paper are: eess
8
The categories of this paper are: hep-ex
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The categories of this paper are: patt-sol
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The categories of this paper are: econ
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The categories of this paper are: solv-int
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The categories of this paper are: chao-dyn
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The categories of this paper are: adap-org
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The categories of this paper are: nlin
34
The categories of this paper are: chem-ph
1
The categories of this paper are: cs
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The categories of this paper are: ao-sci
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The categories of this paper are: cmp-lg