Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Axial Anomaly and the Nucleon Spin   In this letter, we have taken a particular Lagrangian, which was introduced
to resolve U(1) problem, as an effective QCD Lagrangian, and have derived a
formula of the quark content of the nucleon spin. The difference between quark
content of the proton (\Delta\Sigma_p) and that of the neutron (\Delta\Sigma_n)
is evaluated by this formula. Neglecting the higher-order isospin corrections,
this formula can reduce to Efremov's results in the large N_c limit.

17
The categories of this paper are: q-fin
36
The categories of this paper are: cmp-lg
1
The categories of this paper are: cs
31
The categories of this paper are: ao-sci
37
The categories of this paper are: supr-con
16
The categories of this paper are: stat
2
The categories of this paper are: math
21
The categories of this paper are: adap-org
35
The categories of this paper are: mtrl-th
7
The categories of this paper are: hep-th
30
The categories of this paper are: q-alg
6
The categories of this paper are: astro-ph
14
The categories of this paper are: math-ph
5
The categories of this paper are: gr-qc
25
The categories of this paper are: patt-sol
33
The categories of this paper are: plasm-ph