Search for the charmonium semi-leptonic weak decay J/ψ→Ds−e+νe+c.c.

Using a data sample of (10087 ± 44) × 10⁶J/ψ events collected with the BESIII detector at a center-of-mass energy of s=3.097 GeV, a dedicated search for the charmonium semileptonic weak decay J/ψ→Ds−e+νe+c.c. is performed. No significant signal is observed. An upper limit on the branching fraction is set at BJ/ψ→Ds−e+νe+c.c.<9.9×10−8 at the 90% confidence level. This result improves upon previous constraints by an order of magnitude, representing the most stringent experimental limit to date. It thus provides a critical test of Standard Model predictions and new physics scenarios in heavy-quark dynamics.