Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: One-loop finite temperature effective action of QED in the worldline
  approach   The one-loop finite temperature effective potential of QED in an external
electromagnetic field is obtained using the worldline method. The general
structure of the temperature dependent part of the effective action in an
arbitrary external inhomogeneous magnetic field is established. The
two-derivative effective action of spinor and scalar QED in a static magnetic
background at $T\neq 0$ is derived.

21
The categories of this paper are: adap-org
12
The categories of this paper are: nucl-th
13
The categories of this paper are: quant-ph
16
The categories of this paper are: stat
20
The categories of this paper are: acc-phys
31
The categories of this paper are: ao-sci
8
The categories of this paper are: hep-ex
22
The categories of this paper are: chao-dyn
5
The categories of this paper are: gr-qc
37
The categories of this paper are: supr-con
29
The categories of this paper are: funct-an
28
The categories of this paper are: alg-geom
3
The categories of this paper are: physics
35
The categories of this paper are: mtrl-th
18
The categories of this paper are: econ
1
The categories of this paper are: cs