2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/41858We propose a new method to obtain the K -> pi pi amplitude from K -> pi which allows one to fully account for the effects of final state interactions. The method is based on a set of dispersion relations for the K -> pi pi amplitude in which the weak Hamiltonian carries momentum. The soft pion theorem, which relates this amplitude to the K -> pi amplitude, can be used to determine one of the two subtraction constants - the second constant is at present known only to leading order in chiral perturbation theory.Latex, 4 pages, 1 figureHigh Energy Physics - Phenomenologytext