COMPLETELY POSITIVE DYNAMICAL MAPS AND THE NEUTRAL KAON SYSTEM

The evolution of quantum irreversible processes can be effectively des cribed using dynamical semigroups. They involve non-unitary time evolu tions of density matrices that are generated by completely positive ma ps. In the case of the neutral kaon system such an approach leads to a modification of the standard Weisskopf-Wigner evolution, characterize d by six phenomenological parameters. Bounds on the magnitude of these parameters could be given using available experimental data. In this respect, it is remarkable that the condition of complete positivity mi ght be put to a precise test in future more refined experiments.