Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: First Measurement of Chiral Dynamics in \pi^- \gamma -> \pi^- \pi^-
  \pi^+   The COMPASS collaboration at CERN has investigated the \pi^- \gamma -> \pi^-
\pi^- \pi^+ reaction at center-of-momentum energy below five pion masses,
sqrt(s) < 5 m(\pi), embedded in the Primakoff reaction of 190 GeV pions
impinging on a lead target. Exchange of quasi-real photons is selected by
isolating the sharp Coulomb peak observed at smallest momentum transfers, t' <
0.001 (GeV/c)^2. Using partial-wave analysis techniques, the scattering
intensity of Coulomb production described in terms of chiral dynamics and its
dependence on the 3\pi-invariant mass m(3\pi) = sqrt(s) were extracted. The
absolute cross section was determined in seven bins of $\sqrt{s}$ with an
overall precision of 20%. At leading order, the result is found to be in good
agreement with the prediction of chiral perturbation theory over the whole
energy range investigated.

27
The categories of this paper are: comp-gas
14
The categories of this paper are: math-ph
26
The categories of this paper are: bayes-an
12
The categories of this paper are: nucl-th
30
The categories of this paper are: q-alg
16
The categories of this paper are: stat
0
The categories of this paper are: hep-ph
10
The categories of this paper are: q-bio
33
The categories of this paper are: plasm-ph
20
The categories of this paper are: acc-phys
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The categories of this paper are: patt-sol
24
The categories of this paper are: dg-ga
37
The categories of this paper are: supr-con
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The categories of this paper are: mtrl-th
34
The categories of this paper are: chem-ph
11
The categories of this paper are: hep-lat