CPLEAR experiment at CERN: measurement of CP, T and CPT in the neutral kaon system

Using strangeness tagging at production time, CPLEAR measures K0/K0 time-dependent asymmetries in pionic and semileptonic kaon decays. From those, a set of parameters describing CP, T and CPT violation in neutral kaon mixing and decay can be determined. Strangeness tagging at decay time with the lepton charge allows for time-reversal violation to be directly observed with a significance of more than three standard deviations. The precision on each of the CPT violation parameters is discussed. The mass equality of the K0 and K0 is tested within 4.×10−19 GeV.