Precise Measurements of Direct CP Violation, CPT Symmetry, and Other Parameters in the Neutral Kaon System

The authors present precise tests of CP and CPT symmetry based on the full dataset of K → ππ decays collected by the KTeV experiment at Fermi National Accelerator Laboratory during 1996, 1997, and 1999. this dataset contains 16 million K → π0π0 and 69 million K → π+π- decays. They measure the direct CP violation parameter Re(ε(prime)/ε) = (19.2 ± 2.1) x 10-4. They find the KL-KS mass difference Δm = (5270 ± 12) x 106 (hbar)s-1 and the KS lifetime τS = (89.62 ± 0.05) x 10-12 s. They also measure several parameters that test CPT invariance. They find the difference between the phase of the indirect CP violation parameter, ε, and the superweak phase, φε - φSW = (0.40 ± 0.56)o. They measure the difference of the relative phases between the CP violating and CP conserving decay amplitudes for K → π+π- (φ+-) and for K → π0π0 (φ00), Δφ = (0.30 ± 0.35)o. From these phase measurements, they place a limit on the mass difference between K0 and (bar K)0, ΔM < 4.8 x 10-19 GeV/c2 at 95% C.L. These results are consistent with those of other experiments, their own earlier measurements, and CPT symmetry.