Non-Abelian discrete dark matter

Abstract

We consider the minimal model in which dark matter is stabilized by a non-Abelian discrete symmetry. The symmetry group is taken to be D3 ∼ = S3, which is the smallest non-Abelian finite group. The minimal model contains (nontrivial) singlet and doublet scalar representations of D3 which couple to the Standard Model fields via the Higgs portal. This construction predicts two species of dark matter over much of the parameter space. Nontrivial interactions under D3 lead to a novel thermal history of dark matter, while the multi-component nature of dark matter can be tested by future direct detection experiments.Understanding the nature of the cosmological dark matter (DM) that constitutes one quarter of the energy density of the universe is a central goal of particle physics today [1]. While there is little room left to doubt the existence of DM, its microscopic properties are virtually unknown. One of the few properties in which we can be confident is that DM should be stable on time scales greater than the age of the universe, suggesting the existence of a new "dark" symmetry. But precisely what symmetry stabilizes DM is a mystery.Many models employ a discrete Z 2 symmetry to stabilize DM. This Z 2 symmetry is often motivated by the need to suppress dangerous operators in new physics scenarios that solve the hierarchy problem. However, given that we have no experimental indication of what new physics, if any, addresses the naturalness issues in the SM, one may take a more general perspective regarding DM and the symmetries responsible for its stability. More pragmatically, the exploration of alternative stabilizing symmetries is warranted by the prospect of novel phenomena associated with DM, as such symmetries may predict new states and interactions.Indeed, there are many possibilities other than a Z 2parity that can protect DM against decay. In particular, besides the Abelian cyclic symmetry Z N [2], DM may well be stabilized by a non-Abelian discrete symmetry. Non-Abelian finite groups have received some limited attention within the context of DM. Motivated by improved gauge coupling unification, Ref.[3] considered an additional Higgs doublet in a non-Abelian discrete multiplet serving as DM. Non-Abelian discrete symmetries also lead to distinct decay patterns in decaying dark matter scenarios [4,5]. Continuous non-Abelian symmetries originating from broken or confined gauge theories can also ensure DM stability [6]. Models of DM stabilized by Abelian discrete symmetries that descend from higher non-Abelian ones have been motivated by astrophysical anomalies [7], discrete gauge symmetries [8], and neutrino physics [9]. Indeed, non-Abelian flavor symmetries are widely used to explain the neutrino oscillation data [10] (for recent reviews see Refs. [11,12]). Such non-Abelian discrete symmetries can come from the breaking of continuous flavor symmetries [13] or from orbifold compactification of extra-dimensions [14].In this paper we construct the minimal model of DM in which stability is a consequence of a non-Ab...

ℤ3scalar singlet dark matter

“…Complex singlet scalar and Z 3 symmetry have been considered in the context of a model of neutrino mass generation [14], but its DM phenomenology was not studied there. Similar DM phenomenology occurs also in a DM model based on D 3 symmetry [15], but this model is more complicated than the one presented here.…”

Semi-annihilating scalar dark matter

“…With Z 4 and higher, one can have multi-component DM and the so-called DM conversion x i x i ↔ x j x j becomes possible [4,5,6]. This is annihilation, but from one DM component to another.…”

Dark matter within the minimal flavour violation ansatz

“…[29] for a short review. A particular remark should be make on models where more sophisticated global discrete symmetries [30][31][32][33][34][35][36][37][38][39][40][41][42][43][44] and horizontal gauge symmetries [45][46][47][48] have been adopted to deal with the DM phenomenology.…”