Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Unimodular gravity with external sources   The only allowed source of the gravitational field in the unimodular theory,
invariant under area-preserving (transverse) diffeomorphisms as well as Weyl
transformations, is just the traceless piece of the energy-momentum tensor.
This fact notwithstanding, the free energy produced by arbitrary sources (not
only static ones) is identical to the one predicted by general relativity. This
encompasses all weak field tests of gravitation.

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The categories of this paper are: chem-ph
17
The categories of this paper are: q-fin
27
The categories of this paper are: comp-gas
23
The categories of this paper are: solv-int
21
The categories of this paper are: adap-org
20
The categories of this paper are: acc-phys
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The categories of this paper are: cmp-lg
9
The categories of this paper are: nlin
22
The categories of this paper are: chao-dyn
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The categories of this paper are: q-alg
10
The categories of this paper are: q-bio
16
The categories of this paper are: stat
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The categories of this paper are: alg-geom
8
The categories of this paper are: hep-ex
19
The categories of this paper are: eess
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The categories of this paper are: supr-con