Model of TeV scale physics for neutrino mass, dark matter, and baryon asymmetry and its phenomenology

We discuss some details of the model proposed [M. Aoki, S. Kanemura, and O. Seto, Phys. Rev. Lett. 102, 051805 (2009)], in which neutrino oscillation, dark matter, and baryon asymmetry of the Universe would be simultaneously explained by the TeV-scale physics without introducing very high mass scales. An exact discrete $Z_2$ symmetry is introduced, under which new particle contents (a real singlet scalar field, a pair of charged singlet scalar fields, and TeV-scale right-handed neutrinos) are assigned to have odd quantum number, whereas ordinary gauge fields, quarks and leptons, and two Higgs doublets are even. Tiny neutrino masses are generated at the three-loop level due to the exact $Z_2$ symmetry, by which stability of the dark matter candidate is also guaranteed. The extra Higgs doublet is required not only for the tiny neutrino masses but also for successful electroweak baryogenesis. We discuss phenomenological properties of the model, and find that there are successful scenarios in which the above three problems are solved simultaneously under the constraint from current experimental data. We then discuss predictions in such scenarios at ongoing and future experiments. It turns out that the model provides discriminative predictions especially in Higgs physics and dark matter physics, so that it is testable in the near future.

Figure 1

The diagrams for generating tiny neutrino masses.

Figure 2

The contour plot of the values $F$ as a function of $m_N$ and $m_S$ for $m_{\eta }=50\mathrm{GeV}$ and $m_{H^{\pm }}=100\mathrm{GeV}$.

Figure 3

The contour plot of $\mu \to e\gamma$ branching ratio in the $m_N-m_S$ plane for the values of $h_i^{\alpha }$ given in set A to set F.

Figure 4

Feynman diagrams for the DM annihilation. For the one-loop diagrams for $\eta \eta \to \gamma \gamma$ only those which contain the coupling constant $\kappa$ are shown because they give dominant contributions in our parameter choices.

Figure 5

(left) The thermal relic abundance of $\eta$ and contributions from tree and one-loop processes. (right) The thermal relic abundance of $\eta$ and its $m_{S^{\pm }}$ dependence. In both figures, parameters are taken as $(\kappa ,{\sigma }_1,{\sigma }_2,m_h,m_H,\tan \beta )=(3,0.05,0.03,120\mathrm{GeV},100\mathrm{GeV},10)$.

Figure 6

A large enough scattering cross section of light DM with a proton to account for the DAMA/LIBRA claim.

Figure 7

The region of strong first-order EWPT is shown in the $m_A-m_{S^{\pm }}$ plane. The shaded (yellow colored) area is excluded by the condition in Eq. (60). The invariant mass parameters $M$ and ${\mu }_S$ are taken as $M=100\mathrm{GeV}$ and ${\mu }_S=200\mathrm{GeV}$.

Figure 8

Branching ratios of the SM-like Higgs boson $h$ for $\tan \beta =3$ (left) and $\tan \beta =10$ (right) for $\sin (\beta -\alpha )=1$ and $m_{\eta }=48\mathrm{GeV}$. The coupling constants are taken to be ${\sigma }_1=0.05$, ${\sigma }_2=0.03$, ${\rho }_1=1.0$, and ${\rho }_2=1.0$.

Figure 9

The cross section for the scattering process with a proton at the direct search experiment. The upper (lower) curve corresponds to the parameter ${\sigma }_2=0.03(0.01)$. The other parameters are taken to be $m_h=120\mathrm{GeV}$, $m_H=100\mathrm{GeV}$, ${\sigma }_1=0.05$, and $\tan \beta =10$.

Figure 10

The contour plots represent deviations in the $hhh$ coupling from the SM value. For the invariant mass parameters, $M=100\mathrm{GeV}$ and ${\mu }_S=200\mathrm{GeV}$ are taken. The region of the strongly first-order phase transition at this parameter choice is also shown.

Figure 11

Production cross section of a $S^{+}{S}^{-}$ pair via the Drell-Yan process at the LHC ($\sqrt{s}=14\mathrm{TeV}$) as a function of the mass of $S^{\pm }$.

Figure 12

Feynman diagrams for the processes of $e^{+}{e}^{-}\to S^{+}{S}^{-}$ (left) and $e^{-}{e}^{-}\to S^{-}{S}^{-}$ (right).

Figure 13

(left) Production cross sections for $e^{+}{e}^{-}\to S^{+}{S}^{-}$ via the $s$-channel gauge boson ($\gamma$ and $Z$) mediation (dotted curve), the $t$-channel RH-neutrino ($N_R^{\alpha }$) mediation (solid curve), and both contributions (dashed curve) for $\sqrt{s}=300$, 500, and 1000 GeV. The masses for RH neutrinos are taken to be $m_{N_R^1}=m_{N_R^2}=3\mathrm{TeV}$. (right) The angular distribution of the $e^{+}{e}^{-}\to S^{+}{S}^{-}$ at $\sqrt{s}=1\mathrm{TeV}$ for $m_{N_R^1}(=m_{N_R^2})=0.6$, 1, 2, and 3 TeV. In both figures, $h_e^1=h_e^2=2.0$ are taken.

Figure 14

Production cross sections for $e^{-}{e}^{-}\to S^{-}{S}^{-}$ via the $t$-channel RH-neutrino ($N_R^{\alpha }$) mediation (solid curve) for $\sqrt{s}=300$, 500, and 1000 GeV. The masses for RH neutrinos and the relevant coupling constants are taken to be $m_{N_R^1}=m_{N_R^2}=3\mathrm{TeV}$ and $h_e^1=h_e^2=2.0$, respectively.