Search for Nonspectator Decays of theD0

The weak hadronic decay D/sup 0/..-->..K/sup 0/K/sup +/K/sup -/ is observed in a data sample of 9.3 pb/sup -1/ collected with the Mark III detector at the psi(3770) resonance. An analysis of the K/sup +/K/sup -/ subsystem suggests that while the decay proceeds in part through the K-bar/sup 0/phi channel, providing evidence for the presence of nonspectator amplitudes in D/sup 0/ decays, a significant fraction of the decays occur through both higher- and lower-mass K/sup +/K/sup -/ systems. A limit is set on the decay D/sup 0/..-->..K/sup 0/K/sup 0/, also thought to proceed by nonspectator processes.