Speaker
Description
We study the boosted dark matter (BDM) scenario in a two-component model. We consider a neutrinophilic two-Higgs doublet model ($\nu 2$HDM), which comprises of one extra Higgs doublet and a light right-handed neutrino. This model is extended with a light ($\sim 10$ MeV) singlet scalar DM $\phi_3$, which is stabilized under an extra dark $Z_2^{\rm DM}$ symmetry and can only effectively annihilate through the CP even scalar $H$. While the presence of a light scalar $H$ modify the oblique parameters to put tight constraints on the model, introduction of vectorlike leptons (VLL) can potentially salvage the issue. These vectorlike doublet $N$ and vectorlike singlet $\chi$ are also stabilized through the dark $Z_2^{\rm DM}$ symmetry. The lightest vectorlike mass eigenstate ($\chi_1 \sim 100$ GeV) is the second DM component of the model. Individual scalar and fermionic DM candidates have Higgs/$Z$ mediated annihilation, restricting the fermion DM in a narrow mass region while a somewhat broader mass region is allowed for the scalar DM. However, when two DM sectors are coupled, the annihilation channel $\chi_1 \chi_1 \to \phi_3 \phi_3$ opens up. As a result, the fermionic relic density decreases, and paves way for broader fermionic DM mass region with under-abundant relic: a region of $[30-70]$ GeV compared to a narrower $[40-50]$ GeV window for the single component case. On the other hand, the light DM $\phi_3$ acquires significant boost from the annihilation of $\chi_1$, causing a dilution in the resonant annihilation of $\phi_3$. This in turn increases the scalar DM relic allowing a smaller mass region compared to the individual case. The exact and underabundant relic is achievable in a significant parameter space of the two-component model where the total DM relic is mainly dominated by the fermionic DM contribution. The scalar DM is found to be sub-dominant or equally dominant ($\sim 5 \% - 55 \%$ of total DM) with significant boost which can be detected in experiments.
| Track type | Dark Matter |
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