Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Internal Space-time Symmetries of Massless Particles and Neutrino
  Polarization as a Consequence of Gauge Invariance   There are gauge-transformation operators applicable to massless spin-1/2
particles within the little-group framework of internal space-time symmetries
of massive and massless particles. It is shown that two of the $SL(2,c)$
spinors are invariant under gauge transformations while the remaining two are
not. The Dirac equation contains only the gauge-invariant spinors leading to
polarized neutrinos. It is shown that the gauge-dependent $SL(2,c)$ spinor is
the origin of the gauge dependence of electromagnetic four-potentials. It is
noted also that, for spin-1/2 particles, the symmetry group for massless
particles is an infinite-momentum/zero-mass limit of the symmetry group for
massive particles.

10
The categories of this paper are: q-bio
19
The categories of this paper are: eess
31
The categories of this paper are: ao-sci
20
The categories of this paper are: acc-phys
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The categories of this paper are: solv-int
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The categories of this paper are: dg-ga
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The categories of this paper are: funct-an
32
The categories of this paper are: atom-ph
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The categories of this paper are: comp-gas
15
The categories of this paper are: nucl-ex
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The categories of this paper are: adap-org
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The categories of this paper are: q-fin
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The categories of this paper are: chao-dyn
4
The categories of this paper are: cond-mat
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The categories of this paper are: hep-lat
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The categories of this paper are: patt-sol