Cusps in K_L --> 3 pi decays
arXiv:0710.4456 · doi:10.1016/j.physletb.2007.11.008
Abstract
The pion mass difference generates a pronounced cusp in K --> 3 pi decays, the strength of which is related to the pi pi S-wave scattering lengths. We apply an effective field theory framework developed earlier to evaluate the amplitudes for K_L --> 3 pi decays in a systematic manner, where the strictures imposed by analyticity and unitarity are respected automatically. The amplitudes for the decay eta --> 3 pi are also given.
15 pages, 3 figures, uses Elsevier style