A neutral structure in the $D{\overline{D}}^{*}$ system around the $D{\overline{D}}^{*}$ mass threshold is observed with a statistical significance greater than $10\sigma$ in the processes $e^{+}{e}^{-}\to D^{+}{D}^{*-}{\pi }^0+\mathrm{c}\mathrm{.}\mathrm{c}\mathrm{.}$ and $e^{+}{e}^{-}\to D^0{\overline{D}}^{*0}{\pi }^0+\mathrm{c}\mathrm{.}\mathrm{c}\mathrm{.}$ at $\sqrt{s}=4.226$ and 4.257 GeV in the BESIII experiment. The structure is denoted as $Z_c(3885{)}^0$. Assuming the presence of a resonance, its pole mass and width are determined to be $[3885.7_{-5.7}^{+4.3}(\mathrm{stat})\pm 8.4(\mathrm{syst})]\mathrm{MeV}/c^2$ and $[35_{-12}^{+11}(\mathrm{stat})\pm 15(\mathrm{syst})]\mathrm{MeV}$, respectively. The Born cross sections are measured to be $\sigma [e^{+}{e}^{-}\to Z_c(3885{)}^0{\pi }^0,Z_c(3885{)}^0\to D{\overline{D}}^{*}]=[77\pm 13(\mathrm{stat})\pm 17(\mathrm{syst})]\mathrm{pb}$ at 4.226 GeV and $[47\pm 9(\mathrm{stat})\pm 10(\mathrm{syst})]\mathrm{pb}$ at 4.257 GeV. The ratio of decay rates $\mathcal{B}[Z_c(3885{)}^0\to D^{+}{D}^{*-}+\mathrm{c}.\mathrm{c}.]/\mathcal{B}[Z_c(3885{)}^0\to D^0{\overline{D}}^{*0}+\mathrm{c}.\mathrm{c}.]$ is determined to be $0.96\pm 0.18(\mathrm{stat})\pm 0.12(\mathrm{syst})$, consistent with no isospin violation in the process, $Z_c(3885{)}^0\to D{\overline{D}}^{*}$.

• Received 17 September 2015

DOI:https://doi.org/10.1103/PhysRevLett.115.222002