Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Extended Siegert Theorem in the Relativistic Investigation of the
  Deuteron Photodisintegration Reaction   The contribution of the two-body exchange current is investigated for the
reaction of the deuteron photodisintegration in the framework of the
Bethe-Salpeter formalism and with using extended Siegert theorem. This theorem
allow to express the reaction amplitude in terms of extended electric and
magnetic dipole moments of the system. The resultant analytical expression is
faultless with respect to both translation and gauge invariance. It permits to
perform calculations of the deuteron photodisintegration cross section and
polarization observables taking into account two-body exchange current
implicitly.

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The categories of this paper are: nlin
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The categories of this paper are: math-ph
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The categories of this paper are: stat
34
The categories of this paper are: chem-ph
25
The categories of this paper are: patt-sol
32
The categories of this paper are: atom-ph
36
The categories of this paper are: cmp-lg
10
The categories of this paper are: q-bio
18
The categories of this paper are: econ
37
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: cond-mat
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The categories of this paper are: chao-dyn
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The categories of this paper are: bayes-an
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The categories of this paper are: funct-an
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The categories of this paper are: comp-gas