Mini-review of rare charmonium decays at BESIII

Abstract

Recently, the LHCb experiment announced 3.5σ evidence for direct CP violation in D0 decay by looking at the difference between ACP(D0 → K+K−) and ACP(D0 → π+π−). This is the first evidence of CP violation in a charm system, which may indicate new physics beyond the Standard Model. Motivated by this measurement, we review rare processes in charmonium decay, especially, the weak decay, C or P violated decay, and lepton flavor violated decays. In case the new physics appears in charm sector, these rare decays of charmonium states will provide an opportunity to search for significant contributions from physics beyond the Standard Model. With huge J/ψ and ψ (2S) samples in BESIII experiment, the rare decays may be feasible.