Precise measurements of direct CP violation, CPT symmetry, and other parameters in the neutral kaon system

We present precise tests of CP and CPT symmetry based on the full data set of K→ππ decays collected by the KTeV experiment at Fermi National Accelerator Laboratory during 1996, 1997, and 1999. This data set contains 16×106 K→π0π0 and 69×106 K→π⁺π ^- decays. We measure the direct CP violation parameter Re(ε^′/ε)=(19.2±2.1)×10^-4. We find the K_L-K_S mass difference Δm=(5270±12) ×106hs^-1 and the K_S lifetime τ_S=(89. 62±0.05)×10^-12s. We also measure several parameters that test CPT invariance. We find the difference between the phase of the indirect CP violation parameter ε and the superweak phase: φ_ε- φ_SW=(0.40±0.56)°. We 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)°. From these phase measurements, we place a limit on the mass difference between K0 and K^̄0: ΔM<4.8×10^-19GeV/c2 at 95% C.L. These results are consistent with those of other experiments, our own earlier measurements, and CPT symmetry.