Experimental Test of theΔS=ΔQRule in Leptonic Decays of NeutralKMesons

We report the final results of a study of the time distribution of decays of neutral $K$ mesons produced in the reaction $K^{-}+p\to {\overline{K}}^0+n$. We present independent results based on 81 electronic and 38 muonic decays. Combining these with 133 ambiguous events, we find for the $\Delta S=-\Delta Q$ parameter $x$ the value $\mathrm{Re}\mathrm{}\left(x\right)={{0.25}_{-0.09\mathrm{}}}^{+0.07\mathrm{}}$, $\mathrm{Im}\mathrm{}\left(x\right)=0.00\mathrm{}\pm 0.08$. This value lies about 2.5 standard deviations away from the point $x=0\mathrm{}$, and to this extent our experiment suggests a violation of the $\Delta S=\Delta Q$ rule. In the course of an investigation of background processes, we identify and measure the rate of the radiative decay $K_S\to {\pi }^{+}{\pi }^{-}\gamma$.