Observation of a Neutral Structure near the $D\bar{D}^{*}$ Mass Threshold in $e^{+}e^{-}\to (D \bar{D}^*)^0\pi^0$ at $\sqrt{s}$ = 4.226 and 4.257 GeV

TL;DR

This paper reports the observation of a neutral structure, Zc(3885)^0, near the D D* threshold in e+e- collisions at 4.226 and 4.257 GeV, with measurements of its mass, width, and decay properties, providing insights into exotic hadron states.

Contribution

First observation of a neutral Zc(3885)^0 state near the D D* threshold with detailed measurements of its properties and decay ratios in e+e- collisions.

Findings

Zc(3885)^0 observed with >10σ significance

Mass and width of Zc(3885)^0 measured as approximately 3886 MeV/c^2 and 35 MeV

Decay rate ratio indicates no isospin violation

Abstract

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