Probing CPT symmetry in transitions with entangled neutral kaons

Abstract

A new kind of CPT test for transitions in the neutral kaon system is presented, where the exchange of in and out states (and CP conjugation), required for a direct and genuine CPT test, is performed exploiting the entanglement of the kaon pair produced at a ϕ-factory. Using this method it would be possible for the first time to directly test the CPT symmetry in transition processes between meson states, rather than comparing masses, lifetimes, or other intrinsic properties of particle and anti-particle states. The proposed test in the neutral kaon system is very clean and fully robust, and might shed light on possible new CPT violating mechanisms, or further improve the precision of the present experimental limits. It could be implemented at the DAΦNE facility in Frascati, where the KLOE-2 experiment can reach a statistical sensitivity of on the newly proposed observable quantities.