Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Heavy quark pair production in gluon fusion at next-to-next-to-leading
  ${\cal O}(\alpha_s^4)$ order: One-loop squared contributions
30
The categories of this paper are: q-alg
36
The categories of this paper are: cmp-lg
8
The categories of this paper are: hep-ex
10
The categories of this paper are: q-bio
32
The categories of this paper are: atom-ph
21
The categories of this paper are: adap-org
19
The categories of this paper are: eess
31
The categories of this paper are: ao-sci
25
The categories of this paper are: patt-sol
28
The categories of this paper are: alg-geom
6
The categories of this paper are: astro-ph
1
The categories of this paper are: cs
33
The categories of this paper are: plasm-ph
15
The categories of this paper are: nucl-ex
27
The categories of this paper are: comp-gas
37
The categories of this paper are: supr-con