Basic assumptions necessary for the proof of the CPT theorem are considered. It is found that the CPT theorem is not valid for a physical system with unstable particles decaying exponentially. The Lee, Oehme and Yang (LOY) model of neutral kaons decay is discussed and the conclusion is drawn that CPT-transformation cannot be a symmetry in a system which contains the LOY model as a subsystem, and, thus this model is shown to be incapable of describing possible CPT-violation effects correctly. The approximate formulae for matrix elements of the effective Hamiltonian H‖ governing the time evolution in neutral kaons subspace (different from those obtained by means of the Weisskopf–Wigner method and used by LOY) and their implications for an interpretation of the standard CPT-violation parameter [Formula: see text] are considered. Within this approximation it is shown that [Formula: see text] in the system preserving CPT-symmetry and that δ=0 is possible only if [Formula: see text], where H is the total Hamiltonian of the system under consideration, that is, if the system does not preserve CPT-symmetry.
Tests of CPT symmetry and quantum coherence with entangled neutral kaons at KLOE
