Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On exact solutions of the equation for a pion in external fields III   The exact solutions of the equation for a composite scalar particle which
possesses electric and magnetic polarizabilities are found in an external
uniform static magnetic field parallel to the direction of propagation of the
quantized electromagnetic wave. As a particular case, the relativistic coherent
states of a particle in the field of photons were considered. When the average
photon number trends to infinity, the solution tends to the solution
corresponding to the external classical electromagnetic wave with circular
polarization.

28
The categories of this paper are: alg-geom
4
The categories of this paper are: cond-mat
15
The categories of this paper are: nucl-ex
20
The categories of this paper are: acc-phys
24
The categories of this paper are: dg-ga
25
The categories of this paper are: patt-sol
21
The categories of this paper are: adap-org
8
The categories of this paper are: hep-ex
36
The categories of this paper are: cmp-lg
12
The categories of this paper are: nucl-th
29
The categories of this paper are: funct-an
1
The categories of this paper are: cs
11
The categories of this paper are: hep-lat
18
The categories of this paper are: econ
35
The categories of this paper are: mtrl-th
33
The categories of this paper are: plasm-ph