Dispersive representation of K -> 3 pi amplitudes and cusps
Abstract
The NA48/2 collaboration has shown clear experimental evidence for a cusp in the data for K -> pi pi0 pi0. This effect can be used to extract information on the pi-pi scattering lengths. We address this issue using a two-loop dispersive construction of pi pi -> pi pi and K -> pi pi pi amplitudes in the presence of isospin breaking.
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