Linking pseudo-Dirac dark matter to radiative neutrino masses in a singlet-doublet scenario

Abstract

We examine a simple extension of the standard model with a pair of fermions, one singlet and a doublet, in a common thread linking the dark matter problem with the smallness of neutrino masses associated with several exciting features. In the presence of a small bare Majorana mass term, the singlet fermion brings in a pseudo-Dirac dark matter capable of evading the strong spin-independent direct detection bound by suppressing the dark matter annihilation processes mediated by the neutral current. In consequence, the allowed range of a mixing angle between the doublet and the singlet fermions gets enhanced substantially. The presence of the same mass term in an association with singlet scalars also elevates tiny but nonzero masses radiatively for light Majorana neutrino satisfying observed oscillation data.

A dark clue to seesaw and leptogenesis in a pseudo-Dirac singlet doublet scenario with (non)standard cosmology

“…In the present framework the lightest neutral fermion is a viable dark matter candidate which is of pseudo-Dirac nature in the limit m χ L,R M χ . As we see in [45] that this non-vanishing m χ L,R assists in evading strong spin-independent dark matter direct detection bound. In addition, it is also found [45] to be crucial in generating light neutrino mass radiatively.…”

“…The dark sector involves an extended version of the singlet doublet Dirac dark matter [44] framework with the dark matter weakly interacting with the thermal bath. It was earlier shown by us [45] that presence of a small Majorana mass for the singlet fermion in addition to the Dirac mass makes the DM (admixture of singlet and doublet) JHEP03(2021)044 of pseudo Dirac nature. 1 The pseudo-Dirac dark matter is known to leave imprints at the collider in the form of a displaced vertex which can be traced.…”

“…We have shown that eventually the absence of a neutral current at the tree level leads to a substantial improvement for the allowed range of the mixing angle between the singlet and doublet fermion which was otherwise strongly constrained. In [45] we also extend the minimal singlet dark matter set up by inclusion of copies of a dark singlet scalar field to yield light active neutrino masses radiatively. We particularly have emphasized that the Majorana mass term which is related to non observation of DM at direct search experiments can yield the correct order of light neutrino masses.…”

“…The interaction of DM with the SM particles mediated through the Higgs is realized by the first term in eq. (2.7), whereas the second term which is also responsible for active neutrino mass generation through radiative loop [45] manifests the explicit violation of the lepton number. 2 In the present study, we consider…”

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

“…This however requires the addition of Majorana mass terms for the χ field, which are in fact allowed by the symmetry of the model. A similar construction has been exercised recently in [74] in the presence of Majorana masses for both χ L and χ R . Since the very details of neutrino mass expression do not carry a direct connection with the DM and vacuum stability part of our scenario, we refrain from studying the details of neutrino mass here.…”