Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On the theoretical possibility of the electromagnetic scalar potential
  wave spreading with an arbitrary velocity in vacuum   In this work we revisit the process of constructing wave equations for the
scalar and vector potentials of an electromagnetic field, and show that a wave
equation with an arbitrary velocity (including a velocity higher than the
velocity of light in vacuum) for the scalar potential exists in the framework
of classical electrodynamics. Some consequences of this fact are considered. It
is shown (in the Appendix) at what point this work differs from works concerned
of the problem of the gauge invariance in the classical electrodynamics.

14
The categories of this paper are: math-ph
28
The categories of this paper are: alg-geom
7
The categories of this paper are: hep-th
24
The categories of this paper are: dg-ga
21
The categories of this paper are: adap-org
1
The categories of this paper are: cs
2
The categories of this paper are: math
23
The categories of this paper are: solv-int
19
The categories of this paper are: eess
11
The categories of this paper are: hep-lat
22
The categories of this paper are: chao-dyn
17
The categories of this paper are: q-fin
16
The categories of this paper are: stat
33
The categories of this paper are: plasm-ph
12
The categories of this paper are: nucl-th
35
The categories of this paper are: mtrl-th