Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Total cross-section for photon-axion conversions in external
  electromagnetic field   We reconsider the conversion of the photon into axion in the external
electromagnetic fields, namely in the static fields and in a periodic field of
the wave guide. The total cross-sections for the conversion are evaluated in
detail. The result shows that with strong strength of external electromagnetic
fields, the cross-sections are large enough to measure the axion production. In
the wave guide there exists the resonant conversion at the low energies, in
which the value of cross-sections is much enhanced

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The categories of this paper are: supr-con
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The categories of this paper are: chem-ph
16
The categories of this paper are: stat
21
The categories of this paper are: adap-org
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The categories of this paper are: cmp-lg
5
The categories of this paper are: gr-qc
2
The categories of this paper are: math
31
The categories of this paper are: ao-sci
20
The categories of this paper are: acc-phys
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The categories of this paper are: eess
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The categories of this paper are: hep-lat
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The categories of this paper are: solv-int
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The categories of this paper are: patt-sol
14
The categories of this paper are: math-ph
27
The categories of this paper are: comp-gas
32
The categories of this paper are: atom-ph