A Dispersive Treatment of Kℓ4 Decays
1 Albert Einstein Center for Fundamental Physics, Institute for Theoretical Physics, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
2 Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
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Kℓ4 are for several reasons an especially interesting decay channel of K mesons: Kℓ4 decays allow an accurate measurement of a combination of S-wave ππ scattering lengths, one form factor of the decay is connected to the chiral anomaly and the decay is the best source for the determination of some low energy constants of ChPT. We present a dispersive approach to Kℓ4 decays, which takes rescattering effects fully into account. Some fits to NA48/2 and E865 measurements and results of the matching to ChPT are shown.
© Owned by the authors, published by EDP Sciences, 2012
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