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arXiv · hep-ph/0103063

The quark condensate from K_{e_4} decays

G. Colangelo·J. Gasser·H. Leutwyler
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Abstract

We show that, independently of the size of the quark condensate, chiral symmetry correlates the two S-wave ππscattering lengths. In view of this constraint, the new precision data on K_{e_4} decay allow a remarkably accurate determination of these quantities. The result confirms the hypothesis that the quark condensate is the leading order parameter.

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G. Colangelo, J. Gasser, H. Leutwyler. 2001-03-06. The quark condensate from K_{e_4} decays. https://doi.org/10.1103/physrevlett.86.5008

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