Measurement of the branching ratio and a study ofCPfor the leptonic decayKL→e+e−e+e−

We have determined the branching ratio of [ital K][sub [ital L]][r arrow][ital e][sup +][ital e][sup [minus]][ital e][sup +][ital e][sup [minus]] based on the observation of 27 four-electron final state events with 0.36 estimated background event, [ital B]([ital K][sub [ital L]][r arrow][ital e][sup +][ital e][sup [minus]][ital e][sup +][ital e][sup [minus]]) =[3.96[plus minus]0.78(stat)[plus minus]0.32(syst)][times]10[sup [minus]8]. Using the distribution of the angle between the [ital e][sup +][ital e][sup [minus]] pair decay planes, we find that the decay proceeds predominantly through the [ital K][sub 2]([ital CP]=[minus]1) state.