Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Antiproton--proton annihilation into pion pairs within effective meson
  theory
23
The categories of this paper are: solv-int
32
The categories of this paper are: atom-ph
5
The categories of this paper are: gr-qc
37
The categories of this paper are: supr-con
17
The categories of this paper are: q-fin
13
The categories of this paper are: quant-ph
9
The categories of this paper are: nlin
25
The categories of this paper are: patt-sol
11
The categories of this paper are: hep-lat
15
The categories of this paper are: nucl-ex
16
The categories of this paper are: stat
28
The categories of this paper are: alg-geom
24
The categories of this paper are: dg-ga
29
The categories of this paper are: funct-an
21
The categories of this paper are: adap-org
26
The categories of this paper are: bayes-an