Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Four-dimensional aether-like Lorentz-breaking QED revisited and problem
  of ambiguities   In this paper, we consider the perturbative generation of the CPT-even
aether-like Lorentz-breaking term in the extended Lorentz-breaking QED within
different approaches and discuss its ambiguities.

13
The categories of this paper are: quant-ph
4
The categories of this paper are: cond-mat
5
The categories of this paper are: gr-qc
21
The categories of this paper are: adap-org
10
The categories of this paper are: q-bio
36
The categories of this paper are: cmp-lg
31
The categories of this paper are: ao-sci
37
The categories of this paper are: supr-con
24
The categories of this paper are: dg-ga
33
The categories of this paper are: plasm-ph
32
The categories of this paper are: atom-ph
25
The categories of this paper are: patt-sol
6
The categories of this paper are: astro-ph
15
The categories of this paper are: nucl-ex
35
The categories of this paper are: mtrl-th
28
The categories of this paper are: alg-geom