Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Removal of singularities from the covariant spectator theory   A modification of the one boson exchange (OBE) kernel for the covariant
spectator theory (CST) is presented and discussed. When applied to the
scattering of two identical particles, the previously used kernels either
introduced spurious singularities, or removed them in an ad-hoc way. The new
modification not only removes these singularities, but also maintains the
convergence of the two-body CST equation (sometimes called the Gross equation)
when used to describe the scattering of two identical scalar particles.

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The categories of this paper are: physics
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The categories of this paper are: acc-phys
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The categories of this paper are: cs
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The categories of this paper are: eess
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The categories of this paper are: gr-qc
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The categories of this paper are: econ
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The categories of this paper are: nlin
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The categories of this paper are: funct-an
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The categories of this paper are: hep-th
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The categories of this paper are: cmp-lg
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The categories of this paper are: math-ph
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The categories of this paper are: nucl-ex
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The categories of this paper are: hep-ex
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The categories of this paper are: plasm-ph
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The categories of this paper are: chem-ph
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The categories of this paper are: quant-ph