Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Width of photon decay in magnetic field: elementary semiclassical
  derivation and sensitivity to Lorentz violation   We present an elementary derivation of the width of photon decay in a weak
magnetic field using the semiclassical method of worldline instantons. The
calculation is generalized to a model of quantum electrodynamics with broken
Lorentz symmetry. Implications for the search of deviations from Lorentz
invariance in the cosmic ray experiments are discussed.

34
The categories of this paper are: chem-ph
2
The categories of this paper are: math
5
The categories of this paper are: gr-qc
26
The categories of this paper are: bayes-an
25
The categories of this paper are: patt-sol
3
The categories of this paper are: physics
8
The categories of this paper are: hep-ex
36
The categories of this paper are: cmp-lg
13
The categories of this paper are: quant-ph
12
The categories of this paper are: nucl-th
24
The categories of this paper are: dg-ga
29
The categories of this paper are: funct-an
35
The categories of this paper are: mtrl-th
18
The categories of this paper are: econ
4
The categories of this paper are: cond-mat
20
The categories of this paper are: acc-phys