Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Electric current on surface of a metal/superconductor in
  axion/hidden-photon background
4
The categories of this paper are: cond-mat
16
The categories of this paper are: stat
30
The categories of this paper are: q-alg
21
The categories of this paper are: adap-org
17
The categories of this paper are: q-fin
15
The categories of this paper are: nucl-ex
34
The categories of this paper are: chem-ph
36
The categories of this paper are: cmp-lg
35
The categories of this paper are: mtrl-th
33
The categories of this paper are: plasm-ph
2
The categories of this paper are: math
18
The categories of this paper are: econ
14
The categories of this paper are: math-ph
6
The categories of this paper are: astro-ph
29
The categories of this paper are: funct-an
25
The categories of this paper are: patt-sol