M. Ablikim, M. N. Achasov, P. Adlarson, X. C. Ai, R. Aliberti, A. Amoroso, Q. An, Y. Bai, O. Bakina, Y. Ban, H. R. Bao, Batozskaya, K. Begzsuren, N. Berger, M. Berlowski, M. Bertani, D BETTONI, F. Bianchi, E. Bianco, A. Bortone, I. Boyko, R. A. Briere, A. Brueggemann, H. Cai, M. H. Cai, X. Cai, A Calcaterra, G. F. Cao, N. Cao, S. A. Cetin, X. Y. Chai, J. F. Chang, G. R. Che, Y. Z. Che, C Chen, C Chen, G. Chen, H S Chen, H S Chen, M. L. Chen, S. M. Chen, S. L. Chen, S. M. Chen, T T Chen, X. R. Chen, X. R. Chen, X. Y. Chen, Y. Q. Chen, Y. Q. Chen, Y. Q. Chen, Z H Chen, Z. K. Chen, J. C. Cheng, S. K. Choi, X. Chu, G. Cibinetto, F. Cossio, J. Cottee-Meldrum, J. J. Cui, H. L. Dai, J. P. Dai, X. C. Dai, A. Dbeyssi, R. E. de Boer, D. Dedovich, C. Q. Deng, Z. Y. Deng, A. Denig, I. Denysenko, M. Destefanis, F. De Mori, B. Ding, X. X. Ding, Y. Ding, Y. Ding, Yan Ding, J. Dong, L. Y. Dong, M. Y. Dong, X. Dong, M. C. Du, S. X. Du, S. X. Du, Y. Y. Duan, Z. H. Duan, P. Egorov, G. F. Fan, J. J. Fan, Y. H. Fan, J. Fang, J. Fang, S. S. Fang, W. X. Fang, Y. Q. Fang, L. Fava, F Feldbauer, G. Felici, C. Q. Feng, J. H. Feng, L. Feng
A bstract Based on a sample of (10087 ± 44) × 10 6 J / ψ events collected at the center-of-mass energy $$ \sqrt{s}=3.0969 $$ s = 3.0969 GeV with the BESIII detector, we search for the charmonium rare weak decay $$ J/\psi \to {\overline{D}}^0{\overline{K}}^{\ast 0}+\textrm{c}.\textrm{c}. $$ 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.