Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Matter matters in Einstein-Cartan gravity   We study scalar, fermionic and gauge fields coupled nonminimally to gravity
in the Einstein-Cartan formulation. We construct a wide class of models with
nondynamical torsion whose gravitational spectra comprise only the massless
graviton. Eliminating non-propagating degrees of freedom, we derive an
equivalent theory in the metric formulation of gravity. It features contact
interactions of a certain form between and among the matter and gauge currents.
We also discuss briefly the inclusion of curvature-squared terms.

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The categories of this paper are: quant-ph
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The categories of this paper are: cmp-lg
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The categories of this paper are: math
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The categories of this paper are: comp-gas
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The categories of this paper are: patt-sol
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The categories of this paper are: math-ph
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The categories of this paper are: hep-lat
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The categories of this paper are: bayes-an
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The categories of this paper are: eess
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The categories of this paper are: econ
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The categories of this paper are: ao-sci
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The categories of this paper are: funct-an
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The categories of this paper are: nlin
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The categories of this paper are: q-fin
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The categories of this paper are: solv-int
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The categories of this paper are: plasm-ph