Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Magnetic response from constant backgrounds to Coulomb sources   Magnetically uncharged, magnetic linear response of the vacuum filled with
arbitrarily combined constant electric and magnetic fields to an imposed static
electric charge is found within general nonlinear electrodynamics. When the
electric charge is point-like and external fields are parallel, the response
found may be interpreted as a field of two point-like magnetic charges of
opposite polarity in one point. Coefficients characterizing the magnetic
response and induced currents are specialized to Quantum Electrodynamics, where
the nonlinearity is taken as that determined by the Heisenberg-Euler effective
Lagrangian.

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The categories of this paper are: astro-ph
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The categories of this paper are: eess
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The categories of this paper are: cond-mat
14
The categories of this paper are: math-ph
10
The categories of this paper are: q-bio
32
The categories of this paper are: atom-ph
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The categories of this paper are: nlin
22
The categories of this paper are: chao-dyn
35
The categories of this paper are: mtrl-th
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The categories of this paper are: hep-ph
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The categories of this paper are: cs
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The categories of this paper are: econ
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The categories of this paper are: funct-an
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The categories of this paper are: nucl-th
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The categories of this paper are: ao-sci
36
The categories of this paper are: cmp-lg