A bstract Based on a sample of (10087 ± 44) × 10 6 J / ψ events collected at the center-of-mass energy s=3. 0969 s = 3. 0969 GeV with the BESIII detector, we search for the charmonium rare weak decay J/ D⁰K^ 0+c. c. J / ψ → D ¯ 0 K ¯ ∗ 0 + c. c. . No significant signal is observed, and the upper limit on its decay branching fraction at the 90% confidence level is set as 1. 4 × 10 − 7, improving the sensitivity of the previous best limit by an order of magnitude.
Ablikim et al. (Tue,) studied this question.