Abstract
Weakly Interacting Massive Particles (WIMPs) and axions are arguably the most compelling dark matter candidates in the literature. Could they coexist as dark matter particles? More importantly, can they be incorporated in a well motivated framework in agreement with experimental data? In this work, we show that this two component dark matter can be realized in the Inert Doublet Model in an elegant and natural manner by virtue of the spontaneous breaking of a Peccei-Quinn $U(1)_{PQ}$ symmetry into a residual $Z_2$ symmetry. The WIMP stability is guaranteed by the $Z_{2}$ symmetry and a new dark matter component, the axion, arises. There are two interesting outcomes: (i) vector-like quarks needed to implement the Peccei-Quinn symmetry in the model act as a portal between the dark sector and the SM fields with a supersymmetry-type phenomenology at colliders; (ii) two-component Inert Doublet Model re-opens the phenomenologically interesting 100-500 GeV mass region. We show that the model can plausibly have two component dark matter and at the same time avoid low and high energy physics constraints such as monojet and dijet plus missing energy, as well as indirect and direct dark matter detection bounds.
Highlights
Stability is naturally addressed; the strong CP problem in the Standard Model (SM) is solved
Weakly Interacting Massive Particles (WIMPs) and axions are arguably the most compelling dark matter candidates in the literature. Could they coexist as dark matter particles? More importantly, can they be incorporated in a well motivated framework in agreement with experimental data? In this work, we show that this two component dark matter can be realized in the Inert Doublet Model in an elegant and natural manner by virtue of the spontaneous breaking of a Peccei-Quinn U(1)P Q symmetry into a residual Z2 symmetry
Since WIMPs and axions are arguably the most compelling DM candidates in the literature, we investigate the possibility of two component DM in a well motivated model, namely the Inert Doublet Model
Summary
The model consists on a KSVZ type axion model [7, 8] with an inert doublet HD, whose the lightest neutral component is stabilized by a residual ZD2 symmetry that remains unbroken from the original PQ symmetry. The interaction between the dark sector and the SM will be given essentially from the Yukawa term (apart from the interaction term involving the standard Higgs boson and the inert Higgs doublet in the potential), 2We consider that the effective parameters already includes the effects of integrating out the heavy fields at the PQ scale. The spectrum at the electroweak scale which we consider is an inert doublet model [12, 28] augmented by an axion and a vector-like quark D interacting with the particles of the SM through eq (2.6). The first basic constraint comes from the electroweak nature of HD and requires that the SM gauge bosons cannot decay into the dark scalars, i.e., MH0 + MA0 > mZ , MH0 + MH± , MA0 + MH± > mW. Hereunder we discuss collider constraints based on monojet and dijet plus missing energy data from LHC at 7–8 TeV
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