Mayumi Aoki, Jisuke Kubo, Hiroshi Takano
A non-supersymmetric model of two-loop radiative seesaw is proposed. The model contains, in addition to the standard model (SM) Higgs boson, an inert SU(2)_L doublet scalar eta and two inert singlet scalars phi and chi. The lepton number is softly broken by a dimension two operator, and the tree-level Dirac mass is forbidden by Z_2 x Z_2' (or D_{2N}), which predicts the existence of two or three dark matter particles. The scalar sector is minimal; none of the scalar fields can be suppressed for the radiative seesaw mechanism to work. There are by-products: The SM Higgs boson decay into two gamma's is slightly enhanced by eta^+ (the charged component of eta) circulating in one-loop diagrams for h to gamma gamma. The 135 GeV gamma-ray line observed at the Fermi LAT can be also explained by the annihilation of chi dark matter. We employ a mechanism of temperature-dependent annihilation cross section to suppress the continuum gamma-rays and the production of anti-protons. The explanation can survive even down to the XENON1T sensitivity limit.
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http://arxiv.org/abs/1302.3936
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