Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Hint for a minimal interaction length in $e^+e^-\to\gamma\gamma$
  annihilation in total cross section of centre-of-mass energies 55-207 GeV   The measurements of the total cross section of the $ e^+e^-\to\gamma\gamma$
reaction from the VENUS, TOPAS, OPAL, DELPHI, ALEPH and L3 collaborations,
collected between 1989 to 2003, are used to perform a $ \chi^{2} $ test to
search for a finite interaction length in direct contact term. The experimental
data of the total cross section compared to the QED cross section of a $
\chi^{2} $ test allows, to set limit on a finite interaction length $
r_{e}=(1.25\pm 0.16) \times 10 ^{-17} [cm] $. In the direct contact term
annihilation is this interaction lengths a measure for the size of the
electron.

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The categories of this paper are: physics
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The categories of this paper are: q-bio
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The categories of this paper are: nlin
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The categories of this paper are: econ
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The categories of this paper are: nucl-ex
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The categories of this paper are: gr-qc
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The categories of this paper are: acc-phys
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The categories of this paper are: quant-ph
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The categories of this paper are: ao-sci
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The categories of this paper are: funct-an
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The categories of this paper are: comp-gas
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The categories of this paper are: adap-org
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The categories of this paper are: chem-ph
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The categories of this paper are: alg-geom
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The categories of this paper are: hep-lat
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The categories of this paper are: math