An article in Symmetry magazine today suggests the possibility of a new particle at 2 TeV. http://www.symmetrymagazine.org/article/july-2015/something-goes-bump-in-the-data It also contains the quote: "An extended Standard Model predicts comparable particles at higher energies, heavier versions known as W prime and Z prime (or W’ and Z’). Several theorists suggest the bump at 2 TeV could be a type of W prime." The article does not give any other suggestions of what it could be. Is there something in the standard model that prevents a heavier quark or lepton from being discovered? ie. Is there an existing theory or theorist predicting a 4th quark?