  Basic idea of this analysis is to achieve a two-component dark matter (DM)
framework composed of a scalar and a fermion, with non-negligible DM-DM
interaction contributing to thermal freeze out (hence relic density), but
hiding them from direct detection bounds. We therefore augment the Standard
Model (SM) with a scalar singlet ($S$) and three vectorlike fermions: two
singlets ($\chi_1,\chi_2$) and a doublet ($N$). Stability of the two DM
components is achieved by a discrete $\mathcal{Z}_2 \times
{\mathcal{Z}^\prime}_2$ symmetry, under which the additional fields transform
suitably. Fermion fields having same $\mathcal{Z}_2 \times
{\mathcal{Z}^\prime}_2$ charge ($N,\chi_1$ in the model) mix after electroweak
symmetry breaking (EWSB) and the lightest component becomes one of the DM
candidates, while scalar singlet $S$ is the other DM component connected to
visible sector by Higgs portal coupling. The heavy fermion ($\chi_2$) plays the
role of mediator to connect the two DM candidates through Yukawa interaction.
This opens up a large parameter space for the heavier DM component through
DM-DM conversion. Hadronically quiet dilepton signature, arising from the
fermion dark sector, can be observed at Large Hadron Collider (LHC) aided by
the presence of a lighter scalar DM component, satisfying relic density and
direct search bounds through DM-DM conversion.
