Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A Thermal Graviton Background from Extra Dimensions   Inflationary cosmology predicts a low-amplitude graviton background across a
wide range of frequencies. This Letter shows that if one or more extra
dimensions exist, the graviton background may have a thermal spectrum instead,
dependent on the fundamental scale of the extra dimensions. The energy density
is shown to be significant enough that it can affect nucleosynthesis in a
substantial way. The possibility of direct detection of a thermal graviton
background using the 21-cm hydrogen line is discussed. Alternative explanations
for the creation of a thermal graviton background are also examined.

23
The categories of this paper are: solv-int
5
The categories of this paper are: gr-qc
13
The categories of this paper are: quant-ph
36
The categories of this paper are: cmp-lg
19
The categories of this paper are: eess
34
The categories of this paper are: chem-ph
9
The categories of this paper are: nlin
27
The categories of this paper are: comp-gas
37
The categories of this paper are: supr-con
33
The categories of this paper are: plasm-ph
32
The categories of this paper are: atom-ph
2
The categories of this paper are: math
10
The categories of this paper are: q-bio
14
The categories of this paper are: math-ph
17
The categories of this paper are: q-fin
1
The categories of this paper are: cs