Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Study of the process $e^+ e^- \to p \bar p$ via initial state radiation
  at BESIII   The Born cross section for the process $e^+ e^- \to p \bar p $ is measured
using the initial state radiation technique with an undetected photon. This
analysis is based on datasets corresponding to an integrated luminosity of 7.5
fb$^{-1}$, collected with the BESIII detector at the BEPCII collider at center
of mass energies between 3.773 and 4.600 GeV. The Born cross section for the
process $e^+ e^- \to p \bar p $ and the proton effective form factor are
determined in the $p\bar p$ invariant mass range between 2.0 and 3.8 GeV/$c^2$
divided into 30 intervals. The proton form factor ratio ($|G_E|/|G_M|$) is
measured in 3 intervals of the $p\bar p$ invariant mass between 2.0 and 3.0
GeV/$c^2$.

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The categories of this paper are: astro-ph
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The categories of this paper are: math-ph
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The categories of this paper are: stat
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The categories of this paper are: econ
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The categories of this paper are: bayes-an
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The categories of this paper are: alg-geom
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The categories of this paper are: funct-an
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The categories of this paper are: eess
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The categories of this paper are: nlin
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The categories of this paper are: hep-ph
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The categories of this paper are: plasm-ph
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The categories of this paper are: acc-phys
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The categories of this paper are: nucl-ex
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The categories of this paper are: q-bio
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The categories of this paper are: adap-org
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The categories of this paper are: hep-th