Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: An "Accidental" Symmetry Operator for the Dirac Equation in the Coulomb
  Potential
18
The categories of this paper are: econ
3
The categories of this paper are: physics
1
The categories of this paper are: cs
36
The categories of this paper are: cmp-lg
5
The categories of this paper are: gr-qc
22
The categories of this paper are: chao-dyn
21
The categories of this paper are: adap-org
27
The categories of this paper are: comp-gas
25
The categories of this paper are: patt-sol
13
The categories of this paper are: quant-ph
20
The categories of this paper are: acc-phys
32
The categories of this paper are: atom-ph
30
The categories of this paper are: q-alg
17
The categories of this paper are: q-fin
16
The categories of this paper are: stat
33
The categories of this paper are: plasm-ph