Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Causal Propagation of a Charged Spin 3/2 Field in an External
  Electromagnetic Background   We present a Lagrangian for a massive, charged spin 3/2 field in a constant
external electromagnetic background, which correctly propagates only physical
degrees of freedom inside the light cone. The Velo-Zwanziger acausality and
other pathologies such as loss of hyperbolicity or the appearance of unphysical
degrees of freedom are avoided by a judicious choice of non-minimal couplings.
No additional fields or equations besides the spin 3/2 ones are needed to solve
the problem.

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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: acc-phys
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The categories of this paper are: comp-gas
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The categories of this paper are: physics
29
The categories of this paper are: funct-an
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The categories of this paper are: quant-ph
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The categories of this paper are: astro-ph
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The categories of this paper are: supr-con
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The categories of this paper are: nucl-ex
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The categories of this paper are: q-alg
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The categories of this paper are: adap-org
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The categories of this paper are: patt-sol
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The categories of this paper are: math
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The categories of this paper are: econ
14
The categories of this paper are: math-ph