Measurement of the KS lifetime and CPT symmetry tests in the neutral kaon system with quantum interferometry at KLOE

A φ-factory offers the possibility to select pure kaon beams. Neutral kaons from φ → KSKL are produced in a pure J PC = 1- quantum state. Detection of a kaon at large (small) times tags a KS (KL). This allows to perform precise measurement of kaon properties, as for example lifetime, and to study time evolution of neutral kaon system. The distribution of Δt, the difference between the two neutral kaon decay times, where both kaons decay into a π+π- pair, provides unique opportunities for testing quantum mechanics and CPT symmetry. Using the full 2004-2005 data sample (L = 1.5fb-1) collected with the KLOE detector at DAFΦNE, the Frascati e+e- collider, we update results of quantum mechanics and CPT invariance tests. We are finalizing the determination K S lifetimes using about 1/3 the whole KLOE data set. The proper time distribution of KS → π+π- decays provides a competitive measurement of KS meson lifetime.