Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Covariant Majorana Formulation of Electrodynamics   We construct an explicit covariant Majorana formulation of Maxwell
electromagnetism which does not make use of vector 4-potential. This allows to
write a ``Dirac'' equation for the photon containing all the known properties
of it. In particular, the spin and (intrinsic) boost matrices are derived and
the helicity properties of the photon are studied.

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The categories of this paper are: gr-qc
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The categories of this paper are: quant-ph
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The categories of this paper are: patt-sol
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The categories of this paper are: bayes-an
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The categories of this paper are: ao-sci
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The categories of this paper are: comp-gas
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The categories of this paper are: hep-ex
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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: plasm-ph
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The categories of this paper are: eess
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The categories of this paper are: solv-int
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The categories of this paper are: q-bio
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The categories of this paper are: chao-dyn
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The categories of this paper are: acc-phys
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The categories of this paper are: cond-mat