Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: New exact solutions of the Dirac equation of a charged particle
  interacting with an electromagnetic plane wave in a medium   Exact solutions are presented of the Dirac equation of a charged particle
moving in a classical monochromatic electromagnetic plane wave in a medium of
index of refraction n < 1. The found solutions are expressed in terms of new
complex trigonometric polynomials, which form a doubly infinite set labeled by
two integer quantum numbers. These quantum numbers represent quantized spectra
of the energy-momentum components of the charged particle along the
polarization vector and along the propagation direction of the applied
electromagnetic plane wave field (which is considered as a laser field of
arbitrary high intensity, propagating in an underdense plasma). These new
solutions may serve as a basis for the description of possible quantum features
of mechanisms of acceleration of electrons by high-intensity laser fields.

8
The categories of this paper are: hep-ex
16
The categories of this paper are: stat
30
The categories of this paper are: q-alg
15
The categories of this paper are: nucl-ex
27
The categories of this paper are: comp-gas
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
17
The categories of this paper are: q-fin
22
The categories of this paper are: chao-dyn
11
The categories of this paper are: hep-lat
31
The categories of this paper are: ao-sci
10
The categories of this paper are: q-bio
24
The categories of this paper are: dg-ga
28
The categories of this paper are: alg-geom
1
The categories of this paper are: cs