Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Gauge field topology and the hadron spectrum   Topologically non-trivial gauge field configurations are an interesting
aspect of non-abelian gauge theories. These become particularly important upon
quantizing the theory, especially through their effect on the pseudo-scalar
spectrum. These effects are closely tied to chiral anomalies and the
possibility of CP violation in the strong interactions.

34
The categories of this paper are: chem-ph
30
The categories of this paper are: q-alg
19
The categories of this paper are: eess
23
The categories of this paper are: solv-int
37
The categories of this paper are: supr-con
3
The categories of this paper are: physics
14
The categories of this paper are: math-ph
6
The categories of this paper are: astro-ph
0
The categories of this paper are: hep-ph
29
The categories of this paper are: funct-an
22
The categories of this paper are: chao-dyn
7
The categories of this paper are: hep-th
9
The categories of this paper are: nlin
27
The categories of this paper are: comp-gas
36
The categories of this paper are: cmp-lg
4
The categories of this paper are: cond-mat