Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Trans-Planckian Particle Creation in Cosmology and Ultra-High Energy
  Cosmic Rays   We consider observational constraints on creation of particles induced by
hypothetical trans-Planckian effects during the current stage of the Universe
expansion. We show that compatibility with the diffuse gamma-ray background
measured by the EGRET experiment strongly restricts this creation. In
particular, it rules out the possibility to detect signatures of such short
distance effects in anisotropies of the cosmic microwave background radiation.
On the other hand, a possibility that some part of the ultra-high energy cosmic
rays originates from new trans-Planckian physics remains open.

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The categories of this paper are: q-bio
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The categories of this paper are: atom-ph
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The categories of this paper are: solv-int
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The categories of this paper are: chao-dyn
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The categories of this paper are: math-ph
28
The categories of this paper are: alg-geom
37
The categories of this paper are: supr-con
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The categories of this paper are: dg-ga
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The categories of this paper are: q-alg
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The categories of this paper are: patt-sol
35
The categories of this paper are: mtrl-th
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The categories of this paper are: hep-ex
34
The categories of this paper are: chem-ph
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The categories of this paper are: eess
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The categories of this paper are: stat
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The categories of this paper are: q-fin