Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Maxwell-Kosteleck\'y Electromagnetism and Cosmic Magnetization   The Lorentz violating term in the photon sector of Standard Model Extension,
$\mathcal{L}_K = -{$\frac14$} (k_F)_{\alpha \beta \mu \nu} F^{\alpha \beta}
F^{\mu \nu}$ (here referred to as the Kosteleck\'{y} term), breaks conformal
invariance of electromagnetism and enables a superadiabatic amplification of
magnetic vacuum fluctuations during inflation. For a wide range of values of
parameters defining Lorentz symmetry violation and inflation, the present-day
magnetic field can have an intensity of order of nanogauss on megaparsec scales
and then could explain the large-scale magnetization of the universe.

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The categories of this paper are: dg-ga
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The categories of this paper are: gr-qc
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The categories of this paper are: alg-geom
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The categories of this paper are: q-fin
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The categories of this paper are: nlin
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The categories of this paper are: patt-sol
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The categories of this paper are: math-ph
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The categories of this paper are: eess
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The categories of this paper are: econ
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The categories of this paper are: bayes-an
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The categories of this paper are: hep-th
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The categories of this paper are: hep-lat
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The categories of this paper are: nucl-ex
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The categories of this paper are: chem-ph
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The categories of this paper are: adap-org
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The categories of this paper are: q-alg