Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Test of many-electron QED effects in the hyperfine splitting of heavy
  high-Z ions   A rigorous evaluation of the two-photon exchange corrections to the hyperfine
structure in lithiumlike heavy ions is presented. As a result, the theoretical
accuracy of the specific difference between the hyperfine splitting values of
H- and Li-like Bi ions is significantly improved. This opens a possibility for
the stringent test of the many-electron QED effects on a few percent level in
the strongest electromagnetic field presently available in experiments.

5
The categories of this paper are: gr-qc
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The categories of this paper are: nlin
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The categories of this paper are: nucl-th
14
The categories of this paper are: math-ph
28
The categories of this paper are: alg-geom
21
The categories of this paper are: adap-org
33
The categories of this paper are: plasm-ph
2
The categories of this paper are: math
23
The categories of this paper are: solv-int
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The categories of this paper are: hep-ex
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The categories of this paper are: dg-ga
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The categories of this paper are: bayes-an
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The categories of this paper are: q-fin
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The categories of this paper are: eess
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The categories of this paper are: comp-gas
36
The categories of this paper are: cmp-lg