Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Axion Decay of a Photon in an External Electromagnetic Field
6
The categories of this paper are: astro-ph
17
The categories of this paper are: q-fin
36
The categories of this paper are: cmp-lg
15
The categories of this paper are: nucl-ex
31
The categories of this paper are: ao-sci
33
The categories of this paper are: plasm-ph
32
The categories of this paper are: atom-ph
2
The categories of this paper are: math
26
The categories of this paper are: bayes-an
14
The categories of this paper are: math-ph
11
The categories of this paper are: hep-lat
5
The categories of this paper are: gr-qc
25
The categories of this paper are: patt-sol
10
The categories of this paper are: q-bio
21
The categories of this paper are: adap-org
34
The categories of this paper are: chem-ph