Many theories predict that experiments at the Large Hadron Collider (LHC) will find more massive versions of the elementary particles we know.
Almost any grand unified theory – a theory that unites all of the known forces into one – predicts the existence of a particle called Z prime, or Z'. Some of these theories also predict the existence of a particle called W prime, or W'.
Finding W' or Z' could give us clues as to how the forces relate to one another. Or it could give us insight into other physics beyond the Standard Model such as the characteristics of extra dimensions or the mechanism involved in giving elementary particles mass.
The particles in the Standard Model of physics can be separated into two groups, fermions and bosons. Among these elementary particles, fermions are particles of matter, and bosons carry forces. Any interaction between two particles occurs because of the exchange of bosons. Photons carry the electromagnetic force. Bosons called gluons carry the strong nuclear force. And bosons called W and Z carry the weak nuclear force. They are all called gauge bosons for the way they interact. The W and Z are called heavy gauge bosons, as they are decidedly more massive than the other bosons. New heavy gauge bosons could share some properties with the W and the Z.
Observing W' or Z' bosons could have implications in the search for extra dimensions. The size of extra dimensions would be inversely related to the bosons' masses. The smaller the mass of the W' or Z', the larger extra dimensions could be.
The W' and Z' bosons could also free physicists from the need for the Higgs boson, the particle thought to give a coherent description of the masses of elementary particles. At first glance, it seems that the Standard Model requires all elementary particles we know to be massless. But the W and Z bosons are definitively massive particles. At high energies, this challenges first principles of quantum mechanics and special relativity, the two pillars of modern physics. Adding the Higgs boson solves this problem, but so does adding a W' or Z' boson.
Alternatively, the Z' boson could take on the role of dark matter, an invisible substance scientists hypothesize influenced the formation of the universe.
W' or Z' bosons could come in a variety of masses and interact in a variety of ways with other particles. The more physicists learn about new heavy gauge bosons, the better they can determine which theories of new physics could be correct.