BESIII Experiment Identifies X(2370) as a Glueball-Dominated Particle

The BESIII Collaboration at the Beijing Electron Positron Collider has identified the X(2370) particle as predominantly a pseudoscalar glueball with spin-parity quantum numbers of 0⁻⁺. This discovery, announced at the International Conference on High Energy Physics, marks a crucial step in experimentally observing a particle composed entirely of gluons, a long-standing prediction of quantum chromodynamics (QCD), the theory of the strong interaction. The finding, which involved 15 years of research and a large sample of J/ψ particles, aligns with lattice-QCD predictions for a pseudoscalar glueball.