Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Strong CP problem, axions, and cosmological implications of CP violation   In this talk, I present a pedagogical and historical review related to the CP
symmetry. It includes the weak CP violation, the strong CP problem, "invisible"
axions and cosmology, and Type-II leptogenesis.

1
The categories of this paper are: cs
10
The categories of this paper are: q-bio
15
The categories of this paper are: nucl-ex
37
The categories of this paper are: supr-con
4
The categories of this paper are: cond-mat
20
The categories of this paper are: acc-phys
34
The categories of this paper are: chem-ph
28
The categories of this paper are: alg-geom
19
The categories of this paper are: eess
16
The categories of this paper are: stat
31
The categories of this paper are: ao-sci
3
The categories of this paper are: physics
12
The categories of this paper are: nucl-th
21
The categories of this paper are: adap-org
30
The categories of this paper are: q-alg
27
The categories of this paper are: comp-gas