Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Further Evidence for an Increase of the Mean Mass of the Highest-Energy
  Cosmic-Rays with Energy   Sokolsky and D_Avignon have recently reported an examination of a variety of
measurements that relate to the question as to how the mass composition of the
highest-energy cosmic-rays evolves with energy. They assert that cosmic rays
arriving from the Northern Hemisphere have a different mass composition from
those arriving from the Southern Hemisphere, implying a diversity of sources of
high-energy cosmic-rays in the two hemispheres. Were this conclusion to be
correct, it would have profound implications for theories of cosmic-ray origin
and would influence planning of future projects. Their claim thus merits
careful scrutiny. In this paper their analysis is examined in detail with the
verdict being that evidence for a North/South difference is not proven, a
conclusion supported by other data from the Northern and Southern Hemispheres.
However, what is of major importance is that the study of Sokolsky and
D_Avignon provides long-awaited confirmation of the claim that the mean mass of
cosmic rays increases with energy above ~3 E eV made by the Pierre Auger
Collaboration in 2014.

17
The categories of this paper are: q-fin
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The categories of this paper are: solv-int
29
The categories of this paper are: funct-an
2
The categories of this paper are: math
11
The categories of this paper are: hep-lat
1
The categories of this paper are: cs
12
The categories of this paper are: nucl-th
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The categories of this paper are: chao-dyn
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The categories of this paper are: patt-sol
4
The categories of this paper are: cond-mat
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The categories of this paper are: supr-con
30
The categories of this paper are: q-alg
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The categories of this paper are: nucl-ex
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The categories of this paper are: econ
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The categories of this paper are: atom-ph
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The categories of this paper are: dg-ga