Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Dark Radiation and Inflationary Freedom   A relaxed primordial power spectrum (PPS) of scalar perturbations arising
from inflation can impact the dark radiation constraints obtained from Cosmic
Microwave Background and other cosmological measurements. If inflation produces
a non-standard PPS for the initial fluctuations, a fully thermalized light
sterile neutrino can be favoured by CMB observations, instead of being strongly
disfavoured. In the case of a thermal axion, the constraints on the axion mass
are relaxed when the PPS is different from the standard power law.

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The categories of this paper are: gr-qc
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The categories of this paper are: plasm-ph
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The categories of this paper are: cond-mat
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The categories of this paper are: acc-phys
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The categories of this paper are: quant-ph
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The categories of this paper are: q-alg
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The categories of this paper are: hep-lat
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The categories of this paper are: hep-th
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The categories of this paper are: hep-ex
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The categories of this paper are: funct-an
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The categories of this paper are: q-bio
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The categories of this paper are: comp-gas
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The categories of this paper are: dg-ga
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The categories of this paper are: chem-ph
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The categories of this paper are: physics
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The categories of this paper are: eess