Search for the semi-muonic charmonium decay $J/\psi\to D^{-}\mu^{+}\nu_{\mu}+c.c.$

TL;DR

This study searches for a rare semi-muonic decay of the $J/\psi$ particle using a large dataset, setting the first upper limit on its branching fraction due to no significant signal being observed.

Contribution

First search for the weak decay of charmonium involving a muon in the final state, establishing an upper limit on its branching fraction.

Findings

No significant signal observed for the decay.

Upper limit on branching fraction set at $5.6\times10^{-7}$.

First experimental constraint on this decay mode.

Abstract

Using $(10087\pm44)\times10^{6}$ $J/\psi$ events collected with the BESIII detector at the BEPCII $e^+e^-$ storage ring at the center-of-mass energy of $\sqrt{s}=3.097~\rm{GeV}$, we present a search for the rare semi-muonic charmonium decay $J/\psi\to D^{-}\mu^{+}\nu_{\mu}+c.c.$. Since no significant signal is observed, we set an upper limit of the branching fraction to be $\mathcal{B}(J/\psi\to D^{-}\mu^{+}\nu_{\mu}+c.c.)<5.6\times10^{-7}$ at $90\%$ confidence level. This is the first search for the weak decay of charmonium with a muon in the final state.