We report a study of the processes $e^{+}{e}^{-}\to J/\psi D^{(*)}{\overline{D}}^{(*)}$. In $J/\psi D^{*}{\overline{D}}^{*}$ we observe a significant enhancement in the $D^{*}{\overline{D}}^{*}$ invariant mass spectrum, which we interpret as a new charmoniumlike state and denote $X(4160)$. The $X(4160)$ parameters are $M=({4156}_{-20}^{+25}\pm 15)\mathrm{MeV}/c^2$ and $\Gamma =({139}_{-61}^{+111}\pm 21)\mathrm{MeV}$. We also report a new measurement of the $X(3940)$ mass and width: $M=({3942}_{-6}^{+7}\pm 6)\mathrm{MeV}/c^2$ and $\Gamma =({37}_{-15}^{+26}\pm 8)\mathrm{MeV}$. The analysis is based on a $693{\mathrm{fb}}^{-1}$ data sample recorded near the ${\rm Y}(4S)$ resonance by the Belle detector at the KEKB asymmetric-energy collider.

• Received 5 October 2007

DOI:https://doi.org/10.1103/PhysRevLett.100.202001