TeV-scale seesaw mechanisms are interesting due to their potential testability at existing collider experiments. Herein we propose an ${\mathrm{E}}_6$-inspired model allowing a TeV-scale pseudo-Dirac singlet neutrino seesaw mechanism with naturally sizeable Yukawa couplings of $\mathcal{O}({10}^{-2})$. The model also contains new U(1) gauge interactions (and associated $Z^{\prime }$ bosons with which the singlet neutrinos can be produced at colliders), typically long-lived color triplet fermions, SU(2) doublet fermions, and a complex scalar—potentially all at the TeV scale. Additionally we identify three possible explanations for the 750 GeV diphoton excess.

• Received 28 May 2016

DOI:https://doi.org/10.1103/PhysRevD.94.033003