Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Late-time Entropy Production from Scalar Decay and Relic Neutrino
  Temperature   Entropy production from scalar decay in the era of low temperatures after
neutrino decoupling will change the ratio of the relic neutrino temperature to
the CMB temperature, and, hence, the value of N_eff, the effective number of
neutrino species. Such scalar decay is relevant to reheating after thermal
inflation, proposed to dilute massive particles, like the moduli and the
gravitino, featuring in supersymmetric and string theories. The effect of such
entropy production on the relic neutrino temperature ratio is calculated in a
semi-analytic manner, and a recent lower bound on this ratio, obtained from the
WMAP satellite and 2dF galaxy data, is used to set a lower bound of ~ 1.5 x
10^-23 Gev on the scalar decay constant, corresponding to a reheating
temperature of about 3.3 Mev.

21
The categories of this paper are: adap-org
35
The categories of this paper are: mtrl-th
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The categories of this paper are: chao-dyn
1
The categories of this paper are: cs
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The categories of this paper are: bayes-an
2
The categories of this paper are: math
36
The categories of this paper are: cmp-lg
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The categories of this paper are: nucl-th
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The categories of this paper are: math-ph
5
The categories of this paper are: gr-qc
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The categories of this paper are: econ
8
The categories of this paper are: hep-ex
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The categories of this paper are: atom-ph
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The categories of this paper are: chem-ph
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The categories of this paper are: q-fin
3
The categories of this paper are: physics