  I report a recent study done in collaboration with M.E. Peskin, on the time
dependence of a kaon beam propagating according to a generalization of quantum
mechanics due to Ellis, Hagelin, Nanopoulos and Srednicki, in which CP- and
CPT-violating signatures arise from the evolution of pure states to mixed
states. Constraints on the magnitude of its parameters are established on the
basis of existing experimental data. New facilities such as phi-factories are
shown to be particularly adequate to study this generalization from \qm\ and to
disentangle its parameters from other CPT violating perturbations of the kaon
system. ( To appear in Proceedings of the First International Conference on
Phenomenology of Unification from Present to Future, Roma, ITALY -- March
23-26, 1994.)
