Abstract
We suggest a minimal model for GeV-scale Majorana Dark Matter (DM) coupled to the standard model lepton sector via a charged scalar singlet. We show that there is an anti-correlation between the spin-independent DM-Nucleus scattering cross section (σSI) and the DM relic density for parameters values allowed by various theoretical and experimental constraints. Moreover, we find that even when DM couplings are of order unity, σSI is below the current experimental bound but above the neutrino floor. Furthermore, we show that the considered model can be probed at high energy lepton colliders using e.g. the mono-Higgs production and same-sign charged Higgs pair production.
Highlights
Put an end to the most minimal model for GeV-scale Dark Matter (DM) candidate, i.e. the Standard Model (SM) with real scalar singlet [13, 14] which called for several extensions [15, 16]
We minimally extended the SM by two gauge singlets: a charged scalar and a Majorana singlet fermion
We studied the impact of different theoretical and experimental constraints on the model parameter space, and showed that it can be severely constrained by limits from lepton-flavor violating decays at present experiments which in turn would suppress the magnitude of the couplings of the DM
Summary
We consider a minimal extension of the SM which contains, in addition to the SM particle content, two gauge-singlet fields; a charged scalar S and a right handed (RH) neutral fermion N. {V μ, Φ, , q} → {V μ, Φ, , q}, and {S, N } → {−S, −N }, with the condition that N is always lighter than the charged scalar singlet In this simple model, the RH fermion plays the role of the DM candidate while the charged scalar is a mediator of the DM-visible interaction. The RH fermion plays the role of the DM candidate while the charged scalar is a mediator of the DM-visible interaction Under these symmetry requirements, the most general Yukawa Lagrangian can be written as. H which is identified with the recently discovered 125 GeV SM Higgs boson and a pair of charged scalars H± Their tree-level masses are given by: m2H = λ1v2, and m2H ±. Note that (1 + γ5) ΨD, (NR)c (1 − γ5) ΨD where ΨD is a 4 components spinor (i.e. Dirac spinor; which one could denote by just N )
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