Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Parametric co-linear axion photon instability   Axions and axion-like particles generically couple to QED via the
axion-photon-photon interaction. This leads to a modification of Maxwell's
equations known in the literature as axion-electrodynamics. The new form of
Maxwell's equations gives rise to a new parametric instability in which a
strong pump decays into a scattered light wave and an axion. This axion mode
grows exponentially in time and leads to a change in the polarisation of the
initial laser beam, therefore providing a signal for detection. Currently
operating laser systems can put bounds on the axion parameter space, however
longer pulselengths are necessary to reach the current best laboratory bounds
of light-shining through wall experiments.

37
The categories of this paper are: supr-con
27
The categories of this paper are: comp-gas
15
The categories of this paper are: nucl-ex
24
The categories of this paper are: dg-ga
19
The categories of this paper are: eess
13
The categories of this paper are: quant-ph
32
The categories of this paper are: atom-ph
17
The categories of this paper are: q-fin
25
The categories of this paper are: patt-sol
36
The categories of this paper are: cmp-lg
28
The categories of this paper are: alg-geom
12
The categories of this paper are: nucl-th
3
The categories of this paper are: physics
2
The categories of this paper are: math
31
The categories of this paper are: ao-sci
23
The categories of this paper are: solv-int