Search for the charmonium semi-leptonic weak decay $J/\ddot{I}ˆ\to D_s^{-}{e}^{+}\hat{I}{½}_e+c.c.$

Abstract

Using a data sample of $(10087\pm 44)\times 10^6$ $J/\ddot{I}ˆ$ events collected with the BESIII detector at a centre-of-mass energy of $\sqrt{s}=3.097\text{GeV}$, a dedicated search for the charmonium semileptonic weak decay $J/\ddot{I}ˆ\to D_s^{-}{e}^{+}\hat{I}{½}_e+\text{c.c.}$ is performed. No significant signal is observed. An upper limit on the branching fraction is set at $\mathcal{B}(J/\ddot{I}ˆ\to D_s^{-}{e}^{+}\hat{I}{½}_e+\text{c.c.})<9.9\times 10^{-8}$ 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.

18 pages, 4 figures