Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Primordial galactic magnetic fields from domain walls at the QCD phase
  transition
29
The categories of this paper are: funct-an
9
The categories of this paper are: nlin
1
The categories of this paper are: cs
4
The categories of this paper are: cond-mat
8
The categories of this paper are: hep-ex
2
The categories of this paper are: math
18
The categories of this paper are: econ
23
The categories of this paper are: solv-int
13
The categories of this paper are: quant-ph
22
The categories of this paper are: chao-dyn
24
The categories of this paper are: dg-ga
33
The categories of this paper are: plasm-ph
25
The categories of this paper are: patt-sol
16
The categories of this paper are: stat
17
The categories of this paper are: q-fin
3
The categories of this paper are: physics