Search for the rare decay J/ D⁰+c. c. at BESIII

Using (1008744) 10⁶J/ events collected with the BESIII detector, we search for the rare decay J/ D⁰+c. c. for the first time. No obvious signal is observed and the upper limit on the branching fraction is determined to be B (J/ D^0+c. c. ) < 9. 1 10^-8 at 90\% confidence level.