; Zou, Hao
; Lue, Cai-Dian] Chinese Acad Sci, Inst High Energy Phys & Theoret Phys, Ctr Sci Facil, Beijing 100049, Peoples R China
; [Wei, Zheng-Tao
; Li, Xue-Qian] Nankai Univ, Dept Phys, Tianjin 300071, Peoples R China
It is interesting to investigate the weak decays, especially the modes induced by the flavor-changing-neutral currents (FCNC), of a heavy quarkonium in the framework of QCD, because it may provide hints to new mechanisms and/or new physics beyond the standard model (SM). In this work, we calculate the form factors for J/psi -> (D) over bar (()*()0) induced by the FCNC in terms of the QCD sum rules. Making use of these form factors, we further calculate the branching fractions of semileptonic decays, J/psi -> (D) over bar (()*()0)l(+)l(-) (l = e, mu). Our results explicitly expose that the ratio of branching fractions for the channels induced by respectively the weak charged current and FCNC in the J/psi decays is significantly different from that in the case of flavored mesons (D or B), so one may expect to get a better understanding of the non-perturtbative effects in hadronic transitions. Even though such branching ratios are very tiny and beyond the reach of any available facility, because of its importance, it is worth experimental exploration, and we lay hope on the future improvements of facilities of high-energy physics and techniques. Moreover, if such decay modes were observed at the BES III with present luminosity and detection precision, it would be a clear signal for new physics beyond the SM.