Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Non-perturbative vacuum polarization effects in two-dimensional
  supercritical Dirac-Coulomb system. II. Vacuum energy
18
The categories of this paper are: econ
8
The categories of this paper are: hep-ex
36
The categories of this paper are: cmp-lg
32
The categories of this paper are: atom-ph
5
The categories of this paper are: gr-qc
4
The categories of this paper are: cond-mat
12
The categories of this paper are: nucl-th
35
The categories of this paper are: mtrl-th
25
The categories of this paper are: patt-sol
27
The categories of this paper are: comp-gas
31
The categories of this paper are: ao-sci
15
The categories of this paper are: nucl-ex
14
The categories of this paper are: math-ph
22
The categories of this paper are: chao-dyn
21
The categories of this paper are: adap-org
19
The categories of this paper are: eess