Dark matter candidate in an extended type III seesaw scenario

We propose a model with a real $SU(2)$ triplet fermion and a sterile neutrino, both of which are odd under a conserved ${\mathbb{Z}}_2$ symmetry. With all new physics confined to the ${\mathbb{Z}}_2$-odd sector, whose low energy manifestation is in some higher-dimensional operators, a fermionic dark matter candidate is found to emerge. We identify the region of the parameter space of the scenario, which is consistent with all constraints from relic density and direct searches, and allows a wide range of masses for the dark matter candidate.

Figure 1

Relic density $\mathrm{\Omega }{h}^2$ vs. dark matter mass $M_{\chi }$ keeping ${\alpha }_{\mathrm{\Sigma }{\nu }_s}$ fixed at $2.8{\mathrm{TeV}}^{-1}$, $2.9{\mathrm{TeV}}^{-1}$, and $3.0{\mathrm{TeV}}^{-1}$. $M_{\chi }$ is varied by changing the remaining parameter ${\alpha }_{{\nu }_s}$. We use $M_{\mathrm{\Sigma }}=1\mathrm{TeV}$, ${\alpha }_{\mathrm{\Sigma }}=0.1{\mathrm{TeV}}^{-1}$, $M_{{\nu }_s}=200\mathrm{GeV}$. The blue band corresponds to $3\sigma$ variation in relic density according to the $\mathrm{WMAP}+\text{Planck}$ data.

Figure 2

Contour plot in ${\alpha }_{\mathrm{\Sigma }{\nu }_s}\text{−}{\alpha }_{{\nu }_s}$ plane for fixed values of $M_{\mathrm{\Sigma }}=1\mathrm{TeV}$, $M_{{\nu }_s}=200\mathrm{GeV}$, ${\alpha }_{\mathrm{\Sigma }}=0.1{\mathrm{TeV}}^{-1}$. In (a) DM relic density is projected onto the plane, whereas in (b), we project DM mass (in GeV). In both plots the red solid line represents $\mathrm{\Omega }{h}^2=0.1198$ and the dashed red lines correspond to the $3\sigma$ variation in $\mathrm{\Omega }{h}^2$. Darker region corresponds to lower values of $\mathrm{\Omega }{h}^2$ or $M_{\chi }$.

Figure 3

(a) WIMP-nucleon cross section vs. dark matter mass $M_{\chi }$ keeping ${\alpha }_{\mathrm{\Sigma }}$ fixed at $0.1{\mathrm{TeV}}^{-1}$. $M_{\chi }$ is varied by changing the remaining parameters. In such a scenario, DM annihilates via self-annihilation only. $M_{{\nu }_s}$ is varied between 150 and 1000 GeV. (b) WIMP-nucleon cross section vs. dark matter mass $M_{\chi }$ keeping ${\alpha }_{\mathrm{\Sigma }}$ fixed at $0.1{\mathrm{TeV}}^{-1}$. $M_{\chi }$ is varied by changing the remaining parameters. Here coannihilation between the DM candidate with the charged components of the triplet ${\mathrm{\Sigma }}^{\pm }$, the neutral eigenstate of higher mass provides the dominating contribution to relic density. In both the figures different direct detection experimental bounds are indicated and the red points correspond to the $3\sigma$ variation in relic density according to the $\mathrm{WMAP}+\text{Planck}$ data.

Figure 4

(a) WIMP-nucleon cross section vs. dark matter mass $M_{\chi }$ keeping ${\alpha }_{\mathrm{\Sigma }}$ fixed at $0.01{\mathrm{TeV}}^{-1}$. $M_{\chi }$ is varied by changing the remaining parameters. Here self-annihilation of the DM candidate provides the dominating contribution to relic density (b) WIMP-nucleon cross section vs. dark matter mass $M_{\chi }$ keeping ${\alpha }_{\mathrm{\Sigma }}$ fixed at $0.01{\mathrm{TeV}}^{-1}$. $M_{\chi }$ is varied by changing the remaining parameters. Here coannihilation between the DM candidate with the charged components of the triplet ${\mathrm{\Sigma }}^{\pm }$, the neutral eigenstate of higher mass provides the dominating contribution to relic density. In both the figures different direct detection experimental bounds are indicated and the red points correspond to the $3\sigma$ variation in relic density according to the $\mathrm{WMAP}+\text{Planck}$ data.