Search for rare charm decays at BESIII

Abstract: The BESIII experiment searches for rare and symmetry-violating decays with the largest charmonium and threshold open-charm data samples. This contribution reviews recent searches for charmonium weak decays, charm flavour-changing neutral currents, charged-lepton flavour violation, and Bose-symmetry violation. The weak-decay searches have improved several branching-fraction limits, while studies of rare charm-meson and charmonium decays probe flavour-changing neutral currents. Searches for charged-lepton flavour violation set limits in vector and pseudoscalar meson decays and constrain effective interactions. No significant signals are found in any of these searches. The neutral-kaon limits fall below the expectations of a proposed locality scenario, and the $J/ψ$ limit approaches the scale predicted for Standard Model CP violation.