Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Beam-Helicity Asymmetries in Double Pion Photoproduction off the Proton   Beam-helicity asymmetries have been measured at the MAMI accelerator in Mainz
in the three isospin channels $\vec{\gamma}p\to \pi^{+}\pi^0n$,
$\vec{\gamma}p\to \pi^{0}\pi^0p$ and $\vec{\gamma}p\to \pi^{+}\pi^{-}p$ . The
circularly polarized photons, produced from bremsstrahlung of longitudinally
polarized electrons, were tagged with the Glasgow magnetic spectrometer.
Charged pions and the decay photons of $\pi^0$ mesons were detected in a
$~4\pi$ electromagnetic calorimeter which combined the Crystal Ball detector
with the TAPS detector. The precisely measured asymmetries are very sensitive
to details of the production processes and are thus key observables in the
modeling of the reaction dynamics.

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The categories of this paper are: physics
26
The categories of this paper are: bayes-an
31
The categories of this paper are: ao-sci
17
The categories of this paper are: q-fin
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The categories of this paper are: q-bio
32
The categories of this paper are: atom-ph
16
The categories of this paper are: stat
27
The categories of this paper are: comp-gas
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The categories of this paper are: math
13
The categories of this paper are: quant-ph
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The categories of this paper are: math-ph
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The categories of this paper are: hep-lat
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The categories of this paper are: hep-ph
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The categories of this paper are: gr-qc
33
The categories of this paper are: plasm-ph
19
The categories of this paper are: eess