Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The electromagnetic gauge invariance in $SU(3)_L\otimes U(1)_N$ models
  of electroweak unification reexamined   Two models with $SU(3)_C\otimes SU(3)_L\otimes U(1)_N$ gauge symmetry are
considered. We show that the masslessness of the photon does not prevent the
neutrinos from acquiring Majorana masses. That is, there is no relation between
the VEVs of Higgs fields and the electromagnetic gauge invariance contrary to
what has been claimed recently.

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The categories of this paper are: atom-ph
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The categories of this paper are: alg-geom
31
The categories of this paper are: ao-sci
12
The categories of this paper are: nucl-th
6
The categories of this paper are: astro-ph
29
The categories of this paper are: funct-an
27
The categories of this paper are: comp-gas
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The categories of this paper are: chao-dyn
5
The categories of this paper are: gr-qc
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The categories of this paper are: eess
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The categories of this paper are: acc-phys
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The categories of this paper are: q-fin
2
The categories of this paper are: math
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The categories of this paper are: chem-ph
10
The categories of this paper are: q-bio
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The categories of this paper are: cmp-lg