We consider departures from Hamiltonian dynamics in the evolution of neutra
l kaons due to their interactions with environment that generate entangleme
nt among them. We propose a phenomenological model of stochastic re-scatter
ing and estimate the coefficients of the effective Hamiltonian and decohere
nce terms. Finally we analyze the interplay between the weak interaction an
d matter effects and propose the observables suitable to measure the matter
characteristics of CPT violation and decoherence. (C) 2001 Published by El
sevier Science B.V.