Evidence for a never-before-seen particle containing four types of quark has shown up in data from the Tevatron collider at the Fermi National Accelerator Laboratory (Fermilab) in Illinois. The new particle, a class of “tetraquark,” is made of a bottom quark, a strange quark, an up quark and a down quark. The discovery could help elucidate the complex rules that govern quarks—the tiny fundamental particles that make up the protons and neutrons inside all the atoms in the universe.

more at Source: Physicists May Have Discovered a New “Tetraquark” Particle – Scientific American