Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Classical resummation and breakdown of strong-field QED   QED perturbation theory has been conjectured to break down in sufficiently
strong backgrounds, obstructing the analysis of strong-field physics. We show
that the breakdown occurs even in classical electrodynamics, at lower field
strengths than previously considered, and that it may be cured by resummation.
As a consequence, an analogous resummation is required in QED. A detailed
investigation shows, for a range of observables, that unitarity removes
diagrams previously believed to be responsible for the breakdown of QED
perturbation theory.

33
The categories of this paper are: plasm-ph
24
The categories of this paper are: dg-ga
29
The categories of this paper are: funct-an
25
The categories of this paper are: patt-sol
4
The categories of this paper are: cond-mat
10
The categories of this paper are: q-bio
17
The categories of this paper are: q-fin
6
The categories of this paper are: astro-ph
34
The categories of this paper are: chem-ph
28
The categories of this paper are: alg-geom
30
The categories of this paper are: q-alg
32
The categories of this paper are: atom-ph
26
The categories of this paper are: bayes-an
36
The categories of this paper are: cmp-lg
1
The categories of this paper are: cs
21
The categories of this paper are: adap-org