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Cusps in K --> 3 pi decays

Gilberto Colangelo·Juerg Gasser·Bastian Kubis·Akaki Rusetsky
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Abstract

The pion mass difference generates a pronounced cusp in K --> 3 pi decays. As has recently been pointed out by Cabibbo and Isidori, an accurate measurement of the cusp may allow one to pin down the S-wave pi pi scattering lengths to high precision. Here, we present and illustrate an effective field theory framework that allows one to determine the structure of this cusp in a straightforward manner. The strictures imposed by analyticity and unitarity are respected automatically.

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Gilberto Colangelo, Juerg Gasser, Bastian Kubis, Akaki Rusetsky. 2006-04-10. Cusps in K --> 3 pi decays. https://doi.org/10.1016/j.physletb.2006.05.017

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