Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Periodic solutions for the Lorentz force equation with singular
  potentials   We provide sufficient conditions for the existence of periodic solutions of
the of the Lorentz force equation, which models the motion of a charged
particle under the action of an electromagnetic fields. The basic assumptions
cover relevant models with singularities like Coulomb-like electric potentials
or the magnetic dipole.

36
The categories of this paper are: cmp-lg
15
The categories of this paper are: nucl-ex
7
The categories of this paper are: hep-th
0
The categories of this paper are: hep-ph
34
The categories of this paper are: chem-ph
35
The categories of this paper are: mtrl-th
30
The categories of this paper are: q-alg
19
The categories of this paper are: eess
20
The categories of this paper are: acc-phys
22
The categories of this paper are: chao-dyn
24
The categories of this paper are: dg-ga
26
The categories of this paper are: bayes-an
28
The categories of this paper are: alg-geom
11
The categories of this paper are: hep-lat
5
The categories of this paper are: gr-qc
16
The categories of this paper are: stat