  We present an extended version of the Conformal Standard Model (characterized
by the absence of any new intermediate scales between the electroweak scale and
the Planck scale) with an enlarged scalar sector coupling to right-chiral
neutrinos. The scalar potential and the Yukawa couplings involving only
right-chiral neutrinos are invariant under a new global symmetry SU(3)$_N$ that
complements the standard U(1)$_{B-L}$ symmetry, and is broken explicitly only
by the Yukawa interaction, of order $10^{-6}$, coupling right-chiral neutrinos
and the electroweak lepton doublets. We point out four main advantages of this
enlargement, namely: (1) the economy of the (non-supersymmetric) Standard
Model, and thus its observational success, is preserved; (2) thanks to the
enlarged scalar sector the RG improved one-loop effective potential is
everywhere positive with a stable global minimum, thereby avoiding the
notorious instability of the Standard Model vacuum; (3) the pseudo-Goldstone
bosons resulting from spontaneous breaking of the SU(3)$_N$ symmetry are
natural Dark Matter candidates with calculable small masses and couplings; and
(4) the Majorana Yukawa coupling matrix acquires a form naturally adapted to
leptogenesis. The model is made perturbatively consistent up to the Planck
scale by imposing the vanishing of quadratic divergences at the Planck scale
(`softly broken conformal symmetry'). Observable consequences of the model
occur mainly via the mixing of the new scalars and the standard model Higgs
boson.
