Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Dynamic polarizability of Rydberg atoms: Applicability of near-free
  electron approximation, gauge invariance and the Dirac sea
26
The categories of this paper are: bayes-an
7
The categories of this paper are: hep-th
1
The categories of this paper are: cs
4
The categories of this paper are: cond-mat
21
The categories of this paper are: adap-org
35
The categories of this paper are: mtrl-th
9
The categories of this paper are: nlin
17
The categories of this paper are: q-fin
2
The categories of this paper are: math
11
The categories of this paper are: hep-lat
31
The categories of this paper are: ao-sci
15
The categories of this paper are: nucl-ex
8
The categories of this paper are: hep-ex
32
The categories of this paper are: atom-ph
14
The categories of this paper are: math-ph
6
The categories of this paper are: astro-ph