A new study proposes a way to revive the inelastic doublet dark matter (iDM) model, an electroweakly interacting dark matter candidate. This model, which posits the existence of weakly interacting dark matter particles with a small mass difference between their states, had faced strong constraints from solar dark matter capture and direct detection. The proposal arises from the recent observation of the high-energy nuclear recoil event LZ230616, with a recoil energy of approximately 248 keV, which could be a signal of iDM.

The inert lepton doublet (ILD) scenario is an example of iDM that, in its minimal form, predicts the correct relic abundance for dark matter masses in the TeV range. However, these masses are problematic for solar capture and direct detection constraints. The key to this new proposal lies in the incorporation of a type-II seesaw mechanism, which introduces a scalar triplet. This triplet not only generates the necessary mass splitting for iDM but also provides additional annihilation channels. This allows for significantly larger dark matter masses, which in turn helps evade solar capture and indirect detection constraints.

Beyond its role in dark matter, the scalar triplet in the type-II seesaw offers an elegant solution to the neutrino mass problem. This mechanism can generate sub-eV neutrino masses, consistent with neutrino oscillation data. The combination of these two phenomena within a single theoretical framework makes the model an attractive proposal, opening new avenues for the search for dark matter and the understanding of neutrino physics in the context of an extended Standard Model.