Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Pi-Pi Scattering Lengths in the Light of Precision Measurements   I summarize the history of theoretical predictions of, and experimental
attempts to measure, pion-pion (S-wave) scattering lengths. Recent measurements
at CERN confirm Weinberg's 1966 prediction of the I=2 scattering length and
Basdevant and Lee's subsequent correction of the Weinberg I=0 value by
inclusion of an S-wave I=0 resonance.

5
The categories of this paper are: gr-qc
18
The categories of this paper are: econ
7
The categories of this paper are: hep-th
34
The categories of this paper are: chem-ph
14
The categories of this paper are: math-ph
11
The categories of this paper are: hep-lat
27
The categories of this paper are: comp-gas
19
The categories of this paper are: eess
2
The categories of this paper are: math
17
The categories of this paper are: q-fin
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The categories of this paper are: nlin
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The categories of this paper are: astro-ph
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The categories of this paper are: cs
31
The categories of this paper are: ao-sci
20
The categories of this paper are: acc-phys
4
The categories of this paper are: cond-mat