Observation of a New Ds Meson Decaying to DK at a Mass of 2.86 GeV/c2

We observe a new Ds meson with mass (2856.6±1.5stat±5.0syst)  MeV/c2 and width (48±7stat±10syst)  MeV/c2 decaying into D0K+ and D+KS0. In the same mass distributions, we also observe a broad structure with mass (2688±4stat±3syst)  MeV/c2 and width (112±7stat±36syst)  MeV/c2. To obtain this result, we use 240  fb-1 of data recorded by the BABAR detector at the PEP-II asymmetric-energy e+e- storage rings at the Stanford Linear Accelerator Center running at center-of-mass energies near 10.6 GeV.