Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Forward two-photon exchange in elastic lepton-proton scattering and
  hyperfine-splitting correction   We relate the forward two-photon exchange (TPE) amplitudes to integrals of
the inclusive lepton-proton scattering cross sections. These relations yield an
alternative way for the evaluation of the TPE correction to hyperfine-splitting
(HFS) in the hydrogen-like atoms with an equivalent to the standard approach
(Iddings, Drell and Sullivan) result implying the Burkhardt-Cottingham sum
rule. For evaluation of the individual effects (e.g., elastic contribution) our
approach yields a distinct result. We compare both methods numerically on
examples of the elastic contribution and the full TPE correction to HFS in
electronic and muonic hydrogen.

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The categories of this paper are: funct-an
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The categories of this paper are: quant-ph
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The categories of this paper are: ao-sci
8
The categories of this paper are: hep-ex
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The categories of this paper are: chao-dyn
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The categories of this paper are: astro-ph
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The categories of this paper are: adap-org
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The categories of this paper are: cond-mat
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The categories of this paper are: atom-ph
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The categories of this paper are: eess
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The categories of this paper are: acc-phys
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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: q-fin
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The categories of this paper are: q-bio
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The categories of this paper are: hep-lat