Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Strictly finite range forces from the signum-Gordon field: exact results
  in two spatial dimensions   Exact formula for the force between two identical static point charges
coupled to the nonlinear scalar field of two-dimensional signum-Gordon model is
obtained. Pertinent solution of the field equation is found in the form of
one-dimensional integral. The force exactly vanishes when the distance between
the charges exceeds certain critical value.

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The categories of this paper are: nucl-ex
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The categories of this paper are: atom-ph
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The categories of this paper are: econ
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The categories of this paper are: acc-phys
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The categories of this paper are: quant-ph
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The categories of this paper are: hep-ex
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The categories of this paper are: solv-int
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The categories of this paper are: nucl-th
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The categories of this paper are: hep-lat
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The categories of this paper are: math
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The categories of this paper are: mtrl-th
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The categories of this paper are: adap-org
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The categories of this paper are: math-ph
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The categories of this paper are: funct-an
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The categories of this paper are: alg-geom
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The categories of this paper are: chao-dyn