We study the process $e^{+}{e}^{-}\to (D^{*}{\overline{D}}^{*}{)}^{\pm }{\pi }^{\mp }$ at a center-of-mass energy of 4.26 GeV using a $827{\mathrm{pb}}^{-1}$ data sample obtained with the BESIII detector at the Beijing Electron Positron Collider. Based on a partial reconstruction technique, the Born cross section is measured to be $(137\pm 9\pm 15)\mathrm{pb}$. We observe a structure near the $(D^{*}{\overline{D}}^{*}{)}^{\pm }$ threshold in the ${\pi }^{\mp }$ recoil mass spectrum, which we denote as the $Z_c^{\pm }(4025)$. The measured mass and width of the structure are $(4026.3\pm 2.6\pm 3.7)\mathrm{MeV}/{\mathrm{c}}^2$ and $(24.8\pm 5.6\pm 7.7)\mathrm{MeV}$, respectively. Its production ratio $\sigma (e^{+}{e}^{-}\to Z_c^{\pm }(4025){\pi }^{\mp }\to (D^{*}{\overline{D}}^{*}{)}^{\pm }{\pi }^{\mp })/\sigma (e^{+}{e}^{-}\to (D^{*}{\overline{D}}^{*}{)}^{\pm }{\pi }^{\mp })$ is determined to be $0.65\pm 0.09\pm 0.06$. The first uncertainties are statistical and the second are systematic.

• Received 13 August 2013

DOI:https://doi.org/10.1103/PhysRevLett.112.132001