Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Limits on a CP-violating scalar axion-nucleon interaction   Axions or similar hypothetical pseudoscalar bosons may have a small
CP-violating scalar Yukawa interaction g_s(N) with nucleons, causing
macroscopic monopole-dipole forces. Torsion-balance experiments constrain
g_p(e) g_s(N), whereas g_p(N) g_s(N) is constrained by the depolarization rate
of ultra-cold neutrons or spin-polarized nuclei. However, the pseudoscalar
couplings g_p(e) and g_p(N) are strongly constrained by stellar energy-loss
arguments and g_s(N) by searches for anomalous monopole-monopole forces,
together providing the most restrictive limits on g_p(e) g_s(N) and g_p(N)
g_s(N). The laboratory limits on g_s(N) are currently the most restrictive
constraints on CP-violating axion interactions.

9
The categories of this paper are: nlin
6
The categories of this paper are: astro-ph
25
The categories of this paper are: patt-sol
21
The categories of this paper are: adap-org
4
The categories of this paper are: cond-mat
26
The categories of this paper are: bayes-an
15
The categories of this paper are: nucl-ex
35
The categories of this paper are: mtrl-th
28
The categories of this paper are: alg-geom
33
The categories of this paper are: plasm-ph
37
The categories of this paper are: supr-con
36
The categories of this paper are: cmp-lg
3
The categories of this paper are: physics
27
The categories of this paper are: comp-gas
30
The categories of this paper are: q-alg
12
The categories of this paper are: nucl-th