Search for dark sector and rare decays at BESIII

Abstract

The BESIII experiment has collected a large data sample of charmonium, charm mesons, hyperons, and other light mesons. These data provide a unique opportunity to explore the dark sector and rare decays. We present recent dark sector results from the BESIII experiment, including searches for sub-GeV dark matter in $\eta \to \pi^0 + \text{invisible}$ and $J/\psi \to \phi + \text{invisible}$, searches for dark baryon particles in $\Xi^- \to \pi^- +\rm{invisible}$, and searches for light vector bosons in $\chi_{cJ} \to J/\psi X$, where $X \to e^+ e^-$. In addition, we also present the recent rare decay searches, including a search for $\psi \to e \mu$, as well as searches for several baryon number and lepton number violation processes, and searches for various charmonium weak decays.