Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Inverse approach to solutions of the Dirac equation for space-time
  dependent fields   Exact solutions of the Dirac equation in external electromagnetic background
fields are very helpful for understanding non-perturbative phenomena in quantum
electrodynamics (QED). However, for the limited set of known solutions, the
field often depends on one coordinate only, which could be the time $t$, a
spatial coordinate such as $x$ or $r$, or a light-cone coordinate such as
$ct-x$. By swapping the roles of known and unknown quantities in the Dirac
equation, we are able to generate families of solutions of the Dirac equation
in the presence of genuinely space-time dependent electromagnetic fields in
$1+1$ and $2+1$ dimensions.

3
The categories of this paper are: physics
36
The categories of this paper are: cmp-lg
14
The categories of this paper are: math-ph
24
The categories of this paper are: dg-ga
37
The categories of this paper are: supr-con
25
The categories of this paper are: patt-sol
8
The categories of this paper are: hep-ex
12
The categories of this paper are: nucl-th
10
The categories of this paper are: q-bio
32
The categories of this paper are: atom-ph
16
The categories of this paper are: stat
30
The categories of this paper are: q-alg
17
The categories of this paper are: q-fin
19
The categories of this paper are: eess
1
The categories of this paper are: cs
27
The categories of this paper are: comp-gas