Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Massless Cosmic Strings in Expanding Universe   Circular massless cosmic strings which move with the speed of light in the de
Sitter universe are described. Construction of the background geometry is based
on parabolic isometries of the de Sitter spacetime. Microscopic circular cosmic
strings may appear at the Planck epoch and then grow up to the Hubble size. We
analyze: images of the strings, influence of strings on trajectories of matter,
formation of overdensities, and shifts of energies of photons. These effects
allow one to discriminate massless strings from their massive cousins. The
present work extends our results on straight massless cosmic strings in
Minkowsky spacetime to curved backgrounds.

15
The categories of this paper are: nucl-ex
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The categories of this paper are: solv-int
31
The categories of this paper are: ao-sci
2
The categories of this paper are: math
25
The categories of this paper are: patt-sol
20
The categories of this paper are: acc-phys
24
The categories of this paper are: dg-ga
37
The categories of this paper are: supr-con
18
The categories of this paper are: econ
28
The categories of this paper are: alg-geom
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The categories of this paper are: adap-org
10
The categories of this paper are: q-bio
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The categories of this paper are: math-ph
17
The categories of this paper are: q-fin
34
The categories of this paper are: chem-ph
13
The categories of this paper are: quant-ph