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キーワード:
High Energy Physics - Phenomenology, hep-ph
要旨:
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 in such a way that the scalar potential and the Yukawa couplings
involving only right-chiral neutrinos are invariant under a new global symmetry
SU(3)$_N$ which is broken explicitly only by the Yukawa interaction coupling
right-chiral neutrinos and the electroweak lepton doublets. We point out four
main advantages of such an 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. Observable consequences of the model occur
mainly via the mixing of the new scalars and the standard model Higgs boson.
