Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Production of Axions by Cosmic Magnetic Helicity   We investigate the effects of an external magnetic helicity production on the
evolution of the cosmic axion field. It is shown that a helicity larger than
(few \times 10^{-15} G)^2 Mpc, if produced at temperatures above a few GeV, is
in contradiction with the existence of the axion, since it would produce too
much of an axion relic abundance.

27
The categories of this paper are: comp-gas
17
The categories of this paper are: q-fin
29
The categories of this paper are: funct-an
34
The categories of this paper are: chem-ph
15
The categories of this paper are: nucl-ex
18
The categories of this paper are: econ
26
The categories of this paper are: bayes-an
24
The categories of this paper are: dg-ga
30
The categories of this paper are: q-alg
0
The categories of this paper are: hep-ph
21
The categories of this paper are: adap-org
13
The categories of this paper are: quant-ph
4
The categories of this paper are: cond-mat
36
The categories of this paper are: cmp-lg
2
The categories of this paper are: math
16
The categories of this paper are: stat