Observation of a charmoniumlike state produced in association with a J/ψ in e+e- annihilation at √s≈10.6 GeV

We report the first observation of a charmoniumlike state recoiling from the J/psi in the inclusive process e(+)e(-)-> J/psi+anything at a mass of (3.943 +/- 0.006 +/- 0.006) GeV/c(2). We also observe the decay of this state into (DD)-D-* and determine its intrinsic width to be less than 52 MeV/c(2) at the 90% C.L. These results are obtained from a 357 fb(-1) data sample collected with the Belle detector near the Upsilon(4S) resonance, at the KEKB asymmetric-energy e(+)e(-) collider.