‘A long-sought fugitive has been caught at the world’s largest particle accelerator. Experiments at the Large Hadron Collider confirm that a provocative particle called Z(4430) actually exists – and it may be the strongest evidence yet for a new form of matter called a tetraquark.
Quarks are subatomic particles that are the fundamental building blocks of matter. They are known to exist either in groups of two, forming short-lived mesons, or in threes, forming the protons and neutrons that make up atomic nuclei. Researchers have suspected for decades that quarks might also bind together in quartets, forming tetraquarks, but they have not been able to do the complicated quantum calculations necessary to test the idea.’ (New Scientist).