Physicists from CERN’s LHCb Collaboration have discovered a new tetraquark particle, named X(6900), composed of two charm quarks and two charm antiquarks. X(6900), a tetraquark particle composed of two charm quarks and two charm antiquarks. Image credit: CERN. Quarks are point-like elementary particles that typically come in packages of two (mesons) or three (baryons), the most familiar of which are the proton and neutron — each is made of...
