BESIII is the latest incarnation of an experimental programme that began in 1989 when the Beijing Electron Positron Collider (BEPC) and the Beijing Spectrometer (BES) detector started operation at the Institute of High Energy Physics. The focus is on the physics of charm and the τ lepton, which are accessible at the centre-of-mass energies of BEPC. Over the past two decades the BES collaboration has made many important, high-precision measurements, which recently have led to investigations of the puzzling XYZ particles. These particles appear not to fit in the standard picture of charmonium states.

Read more: "BESIII and the XYZ mystery" – CERN Courier