Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A 6-D Brane World Model   We consider a 6D space-time which is periodic in one of the extra dimensions
and compact in the other. The periodic direction is defined by two 4-brane
boundaries. Both static and non-static exact solutions, in which the internal
spacetime has constant radius of curvature, are derived. In the case of static
solutions, the brane tensions must be tuned as in the 5D Randall-Sundrum model,
however, no additional fine-tuning is necessary between the brane tensions and
the bulk cosmological constant. By further relaxing the sole fine-tuning of the
model, we derive non-static solutions, describing de Sitter or Anti de Sitter
4D spacetimes, that allow for the fixing of the inter-brane distance and the
accommodation of pairs of positive-negative and positive-positive tension
branes. Finally, we consider the stability of the radion field in these
configurations by employing small, time-dependent perturbations around the
background solutions. In analogy with results drawn in 5 dimensions, the
solutions describing a de Sitter 4D spacetime turn out to be unstable while
those describing an Anti de Sitter geometry are shown to be stable.

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The categories of this paper are: cond-mat
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The categories of this paper are: comp-gas
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The categories of this paper are: chao-dyn
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The categories of this paper are: math
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The categories of this paper are: supr-con
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The categories of this paper are: ao-sci
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The categories of this paper are: astro-ph
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The categories of this paper are: funct-an
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The categories of this paper are: econ
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The categories of this paper are: bayes-an
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The categories of this paper are: math-ph
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The categories of this paper are: q-fin
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The categories of this paper are: quant-ph
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The categories of this paper are: acc-phys
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The categories of this paper are: physics
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The categories of this paper are: nlin