Minimal two-component scalar doublet dark matter with radiative neutrino mass

We propose a minimal extension of the Standard Model to accommodate two-component dark matter (DM) and light neutrino mass. The symmetry of the Standard Model is enhanced by an unbroken ${\mathbb{Z}}_2\times {\mathbb{Z}}_2^{\prime }$ such that being odd under each ${\mathbb{Z}}_2$, there exists one right-handed neutrino and one inert scalar doublet. Therefore, each of the ${\mathbb{Z}}_2$ sectors contribute to (i) light neutrino masses radiatively similar to the scotogenic models while (ii) the two neutral $CP$ even scalars present in two additional inert doublets play the role of dark matters. Focusing on the intermediate range of inert scalar doublet DM scenario: $M_W\le M_{\mathrm{DM}}\lesssim 500\mathrm{GeV}$, where one scalar doublet DM cannot satisfy correct relic, we show that this entire range becomes allowed within this two-component scalar doublet DM, thanks to the interconversion between the two DM candidates in the presence of neutrino Yukawa couplings with dark sector.

Figure 1

Annihilation channels.

Figure 2

Coannihilation channels.

Figure 3

DM-DM conversion channels.

Figure 4

(Co)annihilation channels in presence of singlet neutral fermions.

Figure 5

Spin independent elastic scattering of DM-nucleon.

Figure 6

Radiative generation of light neutrino mass.

Figure 7

Points which satisfy the correct total DM relic abundance and are allowed by the direct detection constraints for different values of ${\lambda }_{12}$ while maintaining $m_{H_2}>m_{H_1}$.

Figure 8

Relic abundance of DM candidates as a function of $H_1$ mass for fixed benchmark values of other parameters.

Figure 9

Points which satisfies the correct total DM relic abundance and are allowed by the direct detection constraints for different values of ${\lambda }_{12}$ for $\mathrm{\Delta }{M}_2=10\mathrm{GeV}$ while maintaining $m_{H_2}>m_{H_1}$.

Figure 10

(a) Left panel: Spin independent DM-nucleon scattering cross section from our model ($m_{H_2}>m_{H_1}$) for different choices of ${\lambda }_{12}$. Limits from direct detection experiments are shown in black dashed (PandaX-II), dotted (Xenon1T), and solid lines (LUX); (b) Right panel: Indirect detection cross section for $W^{+}{W}^{-}$ final states with different benchmark parameters satisfying the correct relic and direct detection bounds ($m_{H_2}>m_{H_1}$). Upper bounds from Fermi-LAT experiment are denoted by black dashed line.

Figure 11

Points which satisfies the correct total DM relic abundance and are allowed by the direct detection constraints for different values of ${\lambda }_{12}$ while maintaining $m_{H_2}>m_{H_1}$. An analogue of the plots in Fig. 7 in the presence of Yukawa interactions.

Figure 12

Spin independent DM-nucleon scattering cross section as compared to upper limits from direct detection experiments. All points satisfy the total DM relic criteria and $m_{H_2}>m_{H_1}$. An analogue of the plot shown in Fig. 10 in the presence of Yukawa interactions.

Figure 13

Contributions to $\text{Br}(\mu \to e\gamma )$ as a function of DM mass $m_{H_1}$.