Observation of massive ΛKs0π+π+π−− events above 5 GeVc2

Abstract In an experiment using the Fermilab Multiparticle Spectrometer we have studied forward production of high mass events containing two strange particles and charged pions. In the final state ΛK s 0 π + π + π − π − we observe 5 events with effective mass above 5.5 GeV/ c 2 . Four of these events cluster near 5.75 GeV/ c 2 , and three of these events contain K s 0 π + π − mass combinations consistent with the charmed D 0 .