Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The graviton background at early times in string cosmology   We discuss some peculiar properties of the stochastic graviton background
predicted by string cosmology. At Planckian times, for the values of the
parameters of the model which are more interesting for the detection in
gravitational wave experiments, the number density of gravitons is
parametrically large compared to Planck density, and is peaked at small
energies. The large parameter is related to the duration of the string phase
and is a characteristic of string cosmology. The typical interaction time is
parametrically larger than the Planck or string time. Therefore the shape of
the graviton spectrum is not distorted by thermal effects in the Planck era and
can carry informations on the pre-big bang phase suggested by string cosmology.

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The categories of this paper are: hep-th
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The categories of this paper are: stat
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The categories of this paper are: nlin
13
The categories of this paper are: quant-ph
3
The categories of this paper are: physics
35
The categories of this paper are: mtrl-th
27
The categories of this paper are: comp-gas
14
The categories of this paper are: math-ph
17
The categories of this paper are: q-fin
36
The categories of this paper are: cmp-lg
32
The categories of this paper are: atom-ph
0
The categories of this paper are: hep-ph
23
The categories of this paper are: solv-int
34
The categories of this paper are: chem-ph
25
The categories of this paper are: patt-sol
31
The categories of this paper are: ao-sci