Search for the weak decays $J/\psi \to D^{(*)}_{s}e\nu_{e}$

TL;DR

This study searches for rare semi-leptonic weak decays of the J/psi particle into D_s mesons and electrons, setting upper limits on their branching fractions, consistent with Standard Model expectations.

Contribution

First high-sensitivity search for J/psi decays into D_s and D*_s with electron and neutrino, establishing new upper limits on their branching fractions.

Findings

No significant signal observed in either decay channel.

Upper limits on branching fractions are set at 1.3×10^{-6} and 1.8×10^{-6}.

Results align with Standard Model predictions.

Abstract

Using a sample of $2.25\times 10^8$ $J/\psi$ events collected with the BESIII detector at the BEPCII collider, we search for the $J/\psi$ semi-leptonic weak decay $J/\psi \to D^{-}_{s} e^{+}\nu_{e}+c.c.$ with a much higher sensitivity than previous searches. We also perform the first search for $J/\psi \to D^{*-}_{s} e^{+}\nu_{e}+c.c.$ 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 $\mathcal{B}(J/\psi \to D^{-}_{s}e^{+}\nu_{e}+c.c.)<1.3\times10^{-6}$ and $\mathcal{B}(J/\psi \to {D^{*}_{s}}^{-}e^{+}\nu_{e}+c.c.)<1.8\times10^{-6}$, respectively. Both are consistent with Standard Model predictions.