E(6)

An exceptional Lie group studied in advanced Grand Unified Theory (GUT) and string theory model-building. Arising naturally from the E8 × E8 heterotic string, E(6) is a compelling candidate for a GUT symmetry group as it contains SO(10) and SU(5) as subgroups. Its fundamental 27-dimensional representation is remarkably complete, housing all 16 fermions of a single standard model generation from SO(10), plus 11 new exotic particles, including vector-like quarks, new leptons, and a standard model singlet suitable for being a sterile neutrino or a dark matter candidate. This rich particle content can address problems like neutrino mass generation and the matter-antimatter asymmetry. E(6) models often predict interesting phenomenology, such as new particles at accessible energies and specific Z' bosons, making them testable at colliders.