Abstract

We propose a simple model for Dirac neutrinos where the smallness of neutrino mass follows from a parameter kappa whose absence enhances the symmetry of the theory. Symmetry breaking is performed in a two-doublet Higgs sector supplemented by a gauge singlet scalar, realizing an accidental global U(1) symmetry. Its spontaneous breaking at the few TeV scale leads to a physical Nambu -Goldstone - boson the Diracon, denoted D - which is restricted by astrophysics and induces invisible Higgs decays such as h -> DD. The scheme provides a rich, yet very simple scenario for symmetry breaking studies at colliders such as the LHC. (C) 2016 The Authors. Published by Elsevier B.V.