Search for the weak decays $J/\ddot{I}ˆ\to D_s^{(\ast )}e\hat{I}{½}_e$

Abstract

Using a sample of $2.25\times 10^8$ $J/\ddot{I}ˆ$ events collected with the BESIII detector at the BEPCII collider, we search for the $J/\ddot{I}ˆ$ semi-leptonic weak decay $J/\ddot{I}ˆ\to D_s^{-}{e}^{+}\hat{I}{½}_e+c.c.$ with a much higher sensitivity than previous searches. We also perform the first search for $J/\ddot{I}ˆ\to D_s^{\ast -}{e}^{+}\hat{I}{½}_e+c.c.$ No significant excess of a signal above background is observed in either channel. At the $90\%$ confidence level, the upper limits are determined to be $\mathcal{B}(J/\ddot{I}ˆ\to D_s^{-}{e}^{+}\hat{I}{½}_e+c.c.)<1.3\times 10^{-6}$ and $\mathcal{B}(J/\ddot{I}ˆ\to {D_s^{\ast }}^{-}{e}^{+}\hat{I}{½}_e+c.c.)<1.8\times 10^{-6}$, respectively. Both are consistent with Standard Model predictions.

9 pages, 4 figures