Sub-TeV singlet scalar dark matter and electroweak vacuum stability with vectorlike fermions

Abstract

We study a scalar singlet dark matter (DM) having mass in the sub-TeV regime by extending the minimal scalar singlet DM setup by additional vectorlike fermions. While the minimal scalar singlet DM satisfies the relic and direct detection constraints for mass beyond TeV only, presence of its portal coupling with vectorlike fermions opens up additional coannihilation channels. These vectorlike fermions also help in achieving electroweak vacuum stability all the way up to Planck scale. We find that for one generation of vectorlike quarks consisting of a SU(2)L doublet and a singlet, scalar singlet DM with mass a few hundred GeV can indeed satisfy relic, direct detection and other relevant constraints while also making the electroweak vacuum absolutely stable. The same can be achieved by introducing vectorlike leptons too, but with three generations. While the model with vectorlike quarks is minimal, the three generations of vectorlike lepton doublet and neutral singlet can also give rise to light neutrino mass at one loop level.