A detailed description of the analysis of the decay of neutral kaons to ${\mathrm{\pi^+\pi^-}}$ in the CPLEAR experiment

Abstract.

A detailed description is given of the analysis of neutral kaons decaying to ${\mathrm{\pi^+\pi^-}}$, based on the complete set of data collected with the CPLEAR experiment. Using a novel approach involving initially strangeness-tagged ${\mathrm{K^0}}$ and ${\mathrm{\overline{K}^0}}$, the time-dependent decay-rate asymmetry has been measured. This asymmetry, resulting from the interference between the ${\mathrm{K_S}}$ and ${\mathrm{K_L}}$ decay amplitudes, has enabled both the magnitude and phase of the CP-violation parameter, $\eta_{+-}$, to be measured, with a precision comparable to that of the current world-average values.