Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Search for Stimulated Photon-Photon Scattering in Vacuum   We have searched for stimulated photon scattering in vacuum at a center of
mass photon energy of 0.8 eV. The QED contribution to this process is
equivalent to four wave mixing in vacuum. No evidence for gamma-gamma
scattering was observed. The corresponding upper limit of the cross section is
sigma_Lim=1.5 10^{-48}cm2.

27
The categories of this paper are: comp-gas
6
The categories of this paper are: astro-ph
7
The categories of this paper are: hep-th
28
The categories of this paper are: alg-geom
26
The categories of this paper are: bayes-an
10
The categories of this paper are: q-bio
8
The categories of this paper are: hep-ex
32
The categories of this paper are: atom-ph
35
The categories of this paper are: mtrl-th
18
The categories of this paper are: econ
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The categories of this paper are: eess
33
The categories of this paper are: plasm-ph
5
The categories of this paper are: gr-qc
14
The categories of this paper are: math-ph
15
The categories of this paper are: nucl-ex
24
The categories of this paper are: dg-ga