Physicists from the LHCb Collaboration at CERN’s Large Hadron Collider (LHC) have observed four new exotic particles: Zcs(4000)+, Zcs(4220)+, X(4685), and X(4630). The new results provide grist for the mill of theorists seeking to explain the nature of tetraquark binding mechanisms. Illustration of a tetraquark. Imager credit: CERN / CC BY-SA. The new observations take the tally of new hadronic states — including several pentaquarks, rare...
