Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Domain Walls as Dark Energy   The possibility that the energy density of the Universe is dominated by a
network of low-tension domain walls provides an alternative to the commonly
discussed cosmological constant and scalar-field quintessence models of dark
energy. We quantify the lower bound on the number density of the domain walls
that follows from the observed near-isotropy of the cosmic microwave background
radiation. This bound can be satisfied by a strongly frustrated domain wall
network. No fine-tuning of the parameters of the underlying field theory model
is required. We briefly outline the observational consequences of this model.

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The categories of this paper are: comp-gas
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The categories of this paper are: nucl-th
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The categories of this paper are: q-fin
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The categories of this paper are: funct-an
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The categories of this paper are: adap-org
37
The categories of this paper are: supr-con
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The categories of this paper are: eess
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The categories of this paper are: ao-sci
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The categories of this paper are: atom-ph
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The categories of this paper are: stat
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The categories of this paper are: mtrl-th
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The categories of this paper are: acc-phys
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The categories of this paper are: econ
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The categories of this paper are: cmp-lg
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The categories of this paper are: chao-dyn
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The categories of this paper are: dg-ga