Search for the rare semi-leptonic decay $J/\psi\to D^{-}e^{+}\nu_{e}+c.c.$

TL;DR

This study searches for the rare semi-leptonic decay of the $J/\psi$ particle into a $D^{-}$ meson, an electron, and a neutrino, setting a new upper limit that surpasses previous constraints by over two orders of magnitude.

Contribution

The paper provides the most stringent upper limit to date on the branching fraction of the $J/\psi \to D^{-} e^{+} \nu_{e}$ decay, using a large dataset from BESIII.

Findings

No signal observed above background.

Upper limit on branching fraction: $7.1 \times 10^{-8}$.

Improves previous limit by over 100 times.

Abstract

Using $10.1\times10^{9}$ $J/\psi$ events produced by the Beijing Electron Positron Collider (BEPCII) at a center-of-mass energy $\sqrt{s}=3.097~\rm{GeV}$ and collected with the BESIII detector, we present a search for the rare semi-leptonic decay $J/\psi\to D^{-}e^{+}\nu_{e}+c.c.$. No excess of signal above background is observed, and an upper limit on the branching fraction $\mathcal{B}(J/\psi\to D^{-}e^{+}\nu_{e}+c.c.)<7.1\times10^{-8}$ is obtained at $90\%$ confidence level. This is an improvement of more than two orders of magnitude over the previous best limit.