Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The paramagnetic photon. Absence of perpendicular component and decay in
  large fields   Previous results from the authors concerning the arising a tiny photon
anomalous paramagnetic moment $\mu_{\gamma}$ due to its interaction with a
magnetized virtual electron-positron background are complemented and discussed.
It is argued that such magnetic moment it cannot be a linear function of the
angular momentum and that there is no room for the existence of an hypothetical
perpendicular component, as recently claimed in the literature. It is discussed
that in the region beyond the first threshold, where photons may decay in
electron-positron pairs, the photon magnetic moment cannot be defined
independently of the magnetic moment of the created pairs. It is shown that for
magnetic fields large enough, the vacuum becomes unstable and decays also in
electron-positron pairs.

32
The categories of this paper are: atom-ph
6
The categories of this paper are: astro-ph
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The categories of this paper are: plasm-ph
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The categories of this paper are: comp-gas
5
The categories of this paper are: gr-qc
29
The categories of this paper are: funct-an
8
The categories of this paper are: hep-ex
18
The categories of this paper are: econ
7
The categories of this paper are: hep-th
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The categories of this paper are: alg-geom
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The categories of this paper are: q-alg
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The categories of this paper are: nucl-th
4
The categories of this paper are: cond-mat
13
The categories of this paper are: quant-ph
17
The categories of this paper are: q-fin
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The categories of this paper are: dg-ga