Observation of the CP-conserving Ks → π+π−π0 decay amplitude

Abstract The interference between CP-conserving Ks and K L → π + π − π 0 decay amplitudes was observed by studying the decay rate asymmetries between initial K 0 and K 0 separately for the phase space regions E CM ( π + ) > E CM ( π − ) and E CM ( π + ) E CM ( π − ). For the parameter λ we found Re(λ) = 0.036 ± 0.010(stat.) −0.003 +0.002 (syst.) and Im(λ) consistent with zero, leading to a branching ratio B = [4.1 −1.9 +2.5 (stat.) −0.6 +0.5 (syst.)] × 10 −7 for the CP-conserving K S → π + π − π 0 decay.