Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A problem with the Schwinger term in Dirac field theory   In order for Dirac theory to be gauge invariant it can be shown that the
Schwinger term must be zero. However, it can also be shown that for the vacuum
state to be the lowest energy state the Schwinger term must be nonzero.
Therefore there is an inconsistency in Dirac theory involving the evaluation of
the Schwinger term. This inconsistency is discussed along with a possible way
to resolve it.

0
The categories of this paper are: hep-ph
3
The categories of this paper are: physics
6
The categories of this paper are: astro-ph
9
The categories of this paper are: nlin
33
The categories of this paper are: plasm-ph
2
The categories of this paper are: math
1
The categories of this paper are: cs
15
The categories of this paper are: nucl-ex
30
The categories of this paper are: q-alg
11
The categories of this paper are: hep-lat
25
The categories of this paper are: patt-sol
18
The categories of this paper are: econ
5
The categories of this paper are: gr-qc
22
The categories of this paper are: chao-dyn
14
The categories of this paper are: math-ph
32
The categories of this paper are: atom-ph