Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: A variational calculation of particle-antiparticle bound states in the
  scalar Yukawa model
9
The categories of this paper are: nlin
31
The categories of this paper are: ao-sci
22
The categories of this paper are: chao-dyn
30
The categories of this paper are: q-alg
16
The categories of this paper are: stat
5
The categories of this paper are: gr-qc
37
The categories of this paper are: supr-con
4
The categories of this paper are: cond-mat
28
The categories of this paper are: alg-geom
24
The categories of this paper are: dg-ga
26
The categories of this paper are: bayes-an
21
The categories of this paper are: adap-org
19
The categories of this paper are: eess
34
The categories of this paper are: chem-ph
1
The categories of this paper are: cs
36
The categories of this paper are: cmp-lg