Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Pion scattering lengths from NA48   The anomaly (cusp) in the mass spectrum of two neutral pions from the
three-pion decays of charged kaon has been observed in the NA48/2 experiment.
Using the recently developed interpretation of this effect in terms of Chiral
Perturbative Theory, the pion scattering parameters are measured. The
preliminary result for the pion scattering length difference, based on the part
of statistics, is (a0-a2)m(pi+) = 0.281 +/- 0.007 (stat) +/- 0.014(syst) +/-
0.014(extern).

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The categories of this paper are: comp-gas
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The categories of this paper are: plasm-ph
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The categories of this paper are: gr-qc
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The categories of this paper are: patt-sol
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The categories of this paper are: chem-ph
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The categories of this paper are: nlin
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The categories of this paper are: q-alg
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The categories of this paper are: q-fin
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The categories of this paper are: physics
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The categories of this paper are: cond-mat
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The categories of this paper are: mtrl-th
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The categories of this paper are: solv-int
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The categories of this paper are: ao-sci
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The categories of this paper are: hep-ph
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The categories of this paper are: adap-org
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The categories of this paper are: supr-con