Dark Gauge U(1) Symmetry for an Alternative Left-Right Model

An alternative left-right model of quarks and leptons, where the $SU(2)_R$ lepton doublet $(\nu,l)_R$ is replaced with $(n,l)_R$ so that $n_R$ is not the Dirac mass partner of $\nu_L$, has been known since 1987. Previous versions assumed a global $U(1)_S$ symmetry to allow $n$ to be identified as a dark-matter fermion. We propose here a gauge extension by the addition of extra fermions to render the model free of gauge anomalies, and just one singlet scalar to break $U(1)_S$. This results in two layers of dark matter, one hidden behind the other.