Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Complete 2-loop quantum electrodynamic contributions to the muon
  lifetime in the Fermi model   The complete 2-loop QED contributions to the muon lifetime have been
calculated analytically in the Fermi theory. The exact result for the effects
of virtual and real photons, virtual electrons, muons and hadrons as well as
e+e- pair creation is
  Delta Gamma^(2)=Gamma_0(alpha/pi)^2[(156815/5184)-(1036/27)zeta(2)
  -(895/36)zeta(3)+(67/8)zeta(4)
  +53zeta(2)ln(2)-(0.042+/-0.002)]
  where Gamma_0 is the tree-level width. This eliminates the theoretical error
in the extracted value of the Fermi coupling constant, G_F, which was
previously the source of the dominant uncertainty. The new value is
  G_F=(1.16637 +/- 0.00001) x 10^-5 GeV^-2
  with the error being entirely experimental. Several experiments are planned
for the next generation of muon lifetime measurements and these can proceed
unhindered by theoretical uncertainties.

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The categories of this paper are: alg-geom
14
The categories of this paper are: math-ph
32
The categories of this paper are: atom-ph
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The categories of this paper are: chao-dyn
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The categories of this paper are: adap-org
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The categories of this paper are: ao-sci
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The categories of this paper are: bayes-an
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The categories of this paper are: hep-th
4
The categories of this paper are: cond-mat
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The categories of this paper are: eess
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The categories of this paper are: mtrl-th
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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: dg-ga
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The categories of this paper are: patt-sol
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The categories of this paper are: nucl-ex