Search for the FCNC charmonium decay $J/\psi \to D^0 \mu^+ \mu^- + \text{c.c.}$

TL;DR

This study conducted the first search for a rare flavor-changing neutral current decay of the $J/a$ particle into a $D^0$ meson and muons, using a large data sample, but found no signal and set an upper limit on the decay's branching fraction.

Contribution

It provides the first experimental upper limit on the FCNC decay $J/a o D^0 \u03bc^+ \u03bc^-$, expanding the search for new physics in charm quark transitions.

Findings

No significant signal observed.

Upper limit on branching fraction set at $1.1 imes 10^{-7}$.

First search involving muons in this FCNC decay channel.

Abstract

Based on a data sample of $(10087 \pm 44) \times 10^6$ $J/\psi$ events taken with the BESIII detector, we search for the flavor-changing neutral current charmonium decay $J/\psi \to D^{0} \mu^{+} \mu^{-} + \text{c.c.}$. No significant signal above the background is observed, and the upper limit on its branching fraction is set to be $\mathcal{B}(J/\psi \to D^{0}\mu^{+}\mu^{-} + \text{c.c.} ) < 1.1 \times 10^{-7}$ at the 90% confidence level. This marks the first search for a flavor-changing neutral current charmonium decay involving muons in the final state.