Abstract
The radiative neutrino mass model can relate neutrino masses and dark matter at a TeV scale. If we apply this model to thermal leptogenesis, we need to consider resonant leptogenesis at that scale. It requires both finely degenerate masses for the right-handed neutrinos and a tiny neutrino Yukawa coupling. We propose an extension of the model with a U(1) gauge symmetry, in which these conditions are shown to be simultaneously realized through a TeV scale symmetry breaking. Moreover, this extension can bring about a small quartic scalar coupling between the Higgs doublet scalar and an inert doublet scalar which characterizes the radiative neutrino mass generation. It also is the origin of the $Z_2$ symmetry which guarantees the stability of dark matter. Several assumptions which are independently supposed in the original model are closely connected through this extension.
Highlights
ATLAS and CMS groups in the LHC experiment have reported the discovery of the Higgs-like particle [1,2]
We show that (i) both the almost degenerate right-handed neutrino masses and a tiny neutrino Yukawa coupling, which are indispensable for TeV scale resonant leptogenesis [37–40], are brought about after the breaking of this symmetry
We have considered an extension of the radiative neutrino mass model proposed by Ma with a low energy U (1) gauge symmetry
Summary
ATLAS and CMS groups in the LHC experiment have reported the discovery of the Higgs-like particle [1,2]. The existence of neutrino masses and dark matter has been confirmed through various experiments and observations [3–14], it cannot be explained in the standard model. The standard model cannot give a framework for the generation of baryon number asymmetry in the Universe, either [15–17]. A Yukawa coupling of the lightest right-handed neutrino becomes much smaller than that of the heavier one To realize this scenario, we introduce a low energy U (1) gauge symmetry to the model. We find that this extension can explain important key features required in the original Ma model, that is, (ii) a small quartic coupling between the Higgs doublet scalar and an inert doublet scalar which plays a crucial role in the neutrino mass generation, and (iii) the origin of the Z2 symmetry which guarantees the stability of dark matter.
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