Baryons are particles made of three quarks. The quark model predicts the baryon combinations that exist with either spin J=1/2 (this graphic) or spin J=3/2 (not shown). The graphic shows the various three-quark combinations with J=1/2 that are possible using the three lightest quarks–up, down and strange–and the bottom quark. The CDF collaboration announced the discovery of the neutral Xi-sub-b (Ξb0), highlighted in this graphic. Experiments at Fermilab’s Tevatron collider have discovered all of the observed baryons with one bottom quark except the Lambda-sub-b, which was discovered at CERN. There exist additional baryons involving the charm quark, which are not shown in this graphic. The top quark, discovered at Fermilab in 1995, is too short-lived to become part of a baryon.