A search for CP violation in the decays of the neutral Kaons to a positively charged pion, a negatively charged pion, and a neutral pion at the CPLEAR Experiment

A study has been made of the $\pi^{+}\pi^{-}\pi^{0}$ decays of the neutral kaons. The data presented herein were taken during the 1992 and 1993 running of the CPLEAR experiment. A sample of these events has been studied to extract values for the real and imaginary parts of the CP violation parameter $\eta _{+-0} , Re(\eta_{+-0})=0.005\pm 0.024_{stat}\pm 0.007_{syst} (0.0.1) Im(\eta_{+-0})=-0.026\pm 0.035_{stat}\pm 0.013_{syst} (0.0.2)$ Values for these quantities were extracted through a study of the interference between $K^{0}$ and $K^{0}$ decaying into the $\pi^{+}\pi^{-}\pi^{0}$ final state. This was done via a fit of the distribution, $A_{\pi^{+}\pi^{-}\pi^{0}}(t)=\frac{K^{0}(t)-K^{0}(t)}{K^{0}(t)+K^{0}(t)} (0.0.3)$ where the $K^{0}(t)$ and $K^{0}(t)$ are the(acceptance corrected) numbers of $K^{0}$ and $K^{0}$ decaying to $\pi^{+}\pi^{-}\pi^{0}$ as a function of the eigentime of the decay. The analysis which is presented here is based principally on the use of constrained fits. These included fitting the global event information as well as the individual track information to be consistent with energy-momentum conservation and the measured timing information for that event.