Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Leading logarithmic contribution to the second-order Lamb shift induced
  by the loop-after-loop diagram   Contribution of order \alpha^2 (Z \alpha)^6 \ln^3(Z \alpha)^{-2} to the
ground-state Lamb shift in hydrogen induced by the loop-after-loop diagram is
evaluated analytically. An additional contribution of this order is found
compared to the previous calculation by Karshenboim [JETP 76, 541 (1993)]. As a
result, an agreement is achieved for this correction between different
numerical and analytical methods.

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The categories of this paper are: q-bio
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The categories of this paper are: astro-ph
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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: cs
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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: bayes-an
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The categories of this paper are: ao-sci
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The categories of this paper are: comp-gas
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The categories of this paper are: chao-dyn
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The categories of this paper are: acc-phys
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The categories of this paper are: stat
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The categories of this paper are: hep-ex
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The categories of this paper are: nlin
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The categories of this paper are: patt-sol