Observation of a Neutral Structure near the D D ¯ ∗ Mass Threshold in e+e- → (D D ¯ ∗)0π0 at s =4.226 and 4.257 GeV

Abstract

A neutral structure in the DD¯∗ system around the DD¯∗ mass threshold is observed with a statistical significance greater than 10σ in the processes e+e-→D+D∗-π0+c.c. and e+e-→D0D¯∗0π0+c.c. at s=4.226 and 4.257 GeV in the BESIII experiment. The structure is denoted as Zc(3885)0. Assuming the presence of a resonance, its pole mass and width are determined to be [3885.7-5.7+4.3(stat)±8.4(syst)] MeV/c2 and [35-12+11(stat)±15(syst)] MeV, respectively. The Born cross sections are measured to be σ[e+e-→Zc(3885)0π0,Zc(3885)0→DD¯∗]=[77±13(stat)±17(syst)] pb at 4.226 GeV and [47±9(stat)±10(syst)] pb at 4.257 GeV. The ratio of decay rates B[Zc(3885)0→D+D∗-+c.c.]/B[Zc(3885)0→D0D¯∗0+c.c.] is determined to be 0.96±0.18(stat)±0.12(syst), consistent with no isospin violation in the process, Zc(3885)0→DD¯∗.