Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The non-triviality of the vacuum in light-front quantization: An
  elementary treatment   It is often stated that the vacuum is trivial when light-front (null-plane)
quantization is applied to a quantum field theory, in contrast to the situation
with equal-time quantization. In fact, it is has long been known that the
statement is false, and that in certain cases the standard rules for
light-front perturbation theory need modification. This paper gives an
elementary review of these issues, including an explanation of how and when
there is a failure of the elementary derivation of the rules for light-front
perturbation theory.

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The categories of this paper are: ao-sci
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The categories of this paper are: eess
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The categories of this paper are: atom-ph
3
The categories of this paper are: physics
10
The categories of this paper are: q-bio
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The categories of this paper are: hep-lat
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The categories of this paper are: econ
16
The categories of this paper are: stat
30
The categories of this paper are: q-alg
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The categories of this paper are: math-ph
2
The categories of this paper are: math
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The categories of this paper are: solv-int
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The categories of this paper are: chem-ph
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The categories of this paper are: cs
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The categories of this paper are: plasm-ph
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The categories of this paper are: patt-sol