A dispersive treatment of Kℓ4 decays
Albert Einstein Center for Fundamental Physics, Institute for Theoretical Physics, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
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Published online: 26 November 2014
The Kℓ4 decay is one of the best sources of information on some low-energy constants of chiral perturbation theory (χPT). We present a dispersive approach to Kℓ4 decays, which takes rescattering effects fully into account. The dispersion relation treats both experimentally accessible form factors simultaneously and also describes the dependence on the dilepton invariant mass. We apply isospin-breaking corrections before fitting the data of NA48/2 and E865 experiments and extract the values of the low-energy constants L1r, L2r and L3r from a matching to χPT.
© Owned by the authors, published by EDP Sciences, 2014
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