Dispersive treatment of K →ππ

摘要

We write a set of dispersion relations for the K → ππ amplitude in which the weak Hamiltonian carries momentum. A soft pion theorem relates this amplitude to the K →π amplitude, and can be used to determine one of the two subtraction constants ╚D the second constant is at present known only to leading order in chiral perturbation theory. We solve the dispersion relations numerically and express the result in terms of the unknown higher order corrections to this subtraction constant. We present preliminary results of an analysis of the effect of inelastic channels.