Tests of CPT with CPLEAR

Abstract

Measurements of K0/K0 time-dependent asymmetries in pionic and semileptonic decays with the CPLEAR detector enabled a complete determination of CPT violation parameters in the neutral kaon system. A global fit using the Bell-Steinberger relation yielded values for the CPT violation parameter in K0 mixing Im(δ)=(2.4±5.0)×10−5 and Re(δ)=(2.4±2.8)×10−4, the determination of the latter relying essentially on CPLEAR measurements. In addition, CPT violation parameters in semileptonic decays Re(y) and Re(x−) could be measured for the first time. From these results, the equality of K0 and K0 masses and lifetimes is tested at the 10−18 GeV level. Assuming CPT conservation in decays, the 90% C.L. limit on |mK0−mK0| can be pushed down to 5×10−19 GeV. CPT violation amplitudes in I=0 and I=2 decays into two pions were excluded at the level of 10−4 of the corresponding CPT conserving decay amplitudes.