Experimental study of the selection rule ΔS = ΔQ in Koe3 and Koμ3 decays

We have studied the time distribution of semi-leptonic decays of the neutral K meson produced in a hydrogen bubble chamber in the reaction K+p → Kopπ+ with K+ momenta between 1.2 and 1.7 GeV/c. We have identified 306 πev decays and 74 πμv decays of known lepton charge with proper times between 0.04 and 20 KS lifetimes. The results are compatible with no violation of the ΔS = ΔQ rule. For the ratio x of the ΔS = −ΔQ amplitude to the ΔS = ΔQ amplitude we find the values +0.06+0.13inKe3decays:Re⁡xe=0.05inKμ3decays:Re⁡xμ=0.10−0.07−0.16+0.06+0.16Im⁡xe=0.08Im⁡xμ=−0.03−0.07,−0.18. Assuming ΔS = ΔQ we find the rate Γ(KoL → πev + πμv) = (12.4 ± 0.7) × 106 s−1.