Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Radionactive Universe   In a large class of extra-dimensional models, a scalar degree of freedom
known as the radion is long-lived, or even stable, on cosmological scales. In
this paper we investigate the impact of radionactivity on the evolution of the
universe. We demonstrate that whether the radion overcloses the universe,
constitutes the dark matter, is the inflaton, the curvaton, or does not play
any role in cosmology, depends crucially on the ratio between the energy
densities stored in the radion and in the inflaton at the time of inflation. We
discuss the general difficulties reconciling models with low compactification
scale (i.e., TeV scale) with the simple picture of inflation.

37
The categories of this paper are: supr-con
19
The categories of this paper are: eess
31
The categories of this paper are: ao-sci
17
The categories of this paper are: q-fin
33
The categories of this paper are: plasm-ph
22
The categories of this paper are: chao-dyn
34
The categories of this paper are: chem-ph
14
The categories of this paper are: math-ph
30
The categories of this paper are: q-alg
20
The categories of this paper are: acc-phys
7
The categories of this paper are: hep-th
32
The categories of this paper are: atom-ph
26
The categories of this paper are: bayes-an
36
The categories of this paper are: cmp-lg
13
The categories of this paper are: quant-ph
4
The categories of this paper are: cond-mat