Observation of a near-threshold D0(D)over-bar0π0 enhancement in B→D0(D)over-bar0π0K decay

We report the first observation of a near-threshold enhancement in the (DD0)-D-0 pi(0) system from B ->(DD0)-D-0 pi K-0 decays using a 414 fb(-1) data sample collected at the Upsilon(4S) resonance. The enhancement peaks at a mass M=3875.2 +/- 0.7(-1.6)(+0.3)+/- 0.8 MeV/c(2) and the branching fraction for events in the peak is B(B ->(DD0)-D-0 pi K-0)=(1.22 +/- 0.31(+0.23)(-0.30)) x 10(-4). The data were collected with the Belle detector at the KEKB energy-asymmetric e(+)e(-) collider.