Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The charge radii and the decay rates of the pseudoscalar meson   The charge radii and the decay rates of the pion and kaons are calculated,
using the relativistic equation of motion with a linear potential. Those
physical quantities are quite well explained with the current quark masses in
the case of the pion. It is found that the Van Royen-Weisskopf paradox can be
cleared out only in the linear potential model by considering the color degree
of freedom of the quark in the meson. The physical quantities for the kaon are
not so satisfactory that it should be required to reconsider the
Cabibbo-Kobayashi-Maskawa matrix element in the kaon decay.

22
The categories of this paper are: chao-dyn
28
The categories of this paper are: alg-geom
9
The categories of this paper are: nlin
1
The categories of this paper are: cs
7
The categories of this paper are: hep-th
11
The categories of this paper are: hep-lat
35
The categories of this paper are: mtrl-th
29
The categories of this paper are: funct-an
30
The categories of this paper are: q-alg
37
The categories of this paper are: supr-con
31
The categories of this paper are: ao-sci
2
The categories of this paper are: math
18
The categories of this paper are: econ
34
The categories of this paper are: chem-ph
14
The categories of this paper are: math-ph
4
The categories of this paper are: cond-mat