Scale hierarchies, symmetry breaking and particle spectra in SU(3)-family extended SUSY trinification

Abstract

A unification of left-right \rm{SU}(3)_\rm{L}\times \rm{SU}(3)_\rm{R}, colour \rm{SU}(3)_\rm{C} and family \rm{SU}(3)_\rm{F} symmetries in a maximal rank-8 subgroup of ${\mathrm{E}}_8$ is proposed as a landmark for future explorations beyond the Standard Model (SM). We discuss the implications of this scheme in a supersymmetric (SUSY) model based on the trinification gauge ${\left[\mathrm{SU}(3)\right]}^3$ and global \rm{SU}(3)_\rm{F} family symmetries. Among the key properties of this model are the unification of SM Higgs and lepton sectors, a common Yukawa coupling for chiral fermions, the absence of the $\mu$-problem, gauge couplings unification and proton stability to all orders in perturbation theory. The minimal field content consistent with a SM-like effective theory at low energies is composed of one ${\mathrm{E}}_6$ $27$-plet per generation as well as three gauge and one family $\mathrm{SU}(3)$ octets inspired by the fundamental sector of ${\mathrm{E}}_8$. The details of the corresponding (SUSY and gauge) symmetry breaking scheme, multi-scale gauge couplings' evolution, and resulting effective low-energy scenarios are discussed.

Comments: 31 pages, 3 figures; discussion of particle mass hierarchies at low energies expanded; the version accepted to Phys. Rev. D