Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Several solutions of the Klein-Gordon equation in Kerr-Newman spacetime
  and the BSW effect
4
The categories of this paper are: cond-mat
26
The categories of this paper are: bayes-an
17
The categories of this paper are: q-fin
0
The categories of this paper are: hep-ph
13
The categories of this paper are: quant-ph
3
The categories of this paper are: physics
34
The categories of this paper are: chem-ph
27
The categories of this paper are: comp-gas
29
The categories of this paper are: funct-an
10
The categories of this paper are: q-bio
32
The categories of this paper are: atom-ph
36
The categories of this paper are: cmp-lg
33
The categories of this paper are: plasm-ph
16
The categories of this paper are: stat
8
The categories of this paper are: hep-ex
2
The categories of this paper are: math