Exceptional unification of families and forces

Abstract

This work considers the remarkable suggestion that the three families of quarks and leptons may be unified, together with the Higgs and gauge fields of the Standard Model (SM), into a single “particle”, namely the 248 vector superfield of a ten-dimensional E8 super Yang Mills (SYM) theory. Towards a realistic model along these lines, a class of orbifoldings based on T6/(ZN×ZM) are proposed and explored, that can in principle break E8 SYM down to the minimal supersymmetric standard model (MSSM), embedded in a larger group such as E6, SO(10) or SU(5), together with other gauge group factors which can be broken by Wilson lines. A realistic model based on T6/(Z6×Z2) is presented. The orbifold breaks E8 SYM down to a Pati-Salam gauge group in 4d, together with other gauge groups, which are subsequently broken to the SM gauge group with proto-realistic fermion mass matrices, and experimental signals associated with a low Pati-Salam scale.