Dark matter from freeze-in via the neutrino portal

J. Cosmol. Astropart. Phys.

2018

We propose a minimal model to simultaneously account for a realistic neutrino spectrum through a type-I seesaw mechanism and a viable dark matter relic density. The model is an extension of the Littlest Seesaw model in which the two right-handed neutrinos of the model are coupled to a Z 2-odd dark sector via right-handed neutrino portal couplings. In this model, a highly constrained and direct link between dark matter and neutrino physics is achieved by considering the freeze-in production mechanism of dark matter. We show that the neutrino Yukawa couplings which describe neutrino mass and mixing may also play a dominant role in the dark matter production. We investigate the allowed regions in the parameter space of the model that provide the correct neutrino masses and mixing and simultaneously give the correct dark matter relic abundance. In certain cases the right-handed neutrino mass may be arbitrarily large, for example in the range 10 10 − 10 11 GeV required for vanilla leptogenesis, with a successful relic density arising from frozen-in dark matter particles with masses around this scale, which we refer to as "fimpzillas".

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confidence: 99%

The dark side of the Littlest Seesaw: freeze-in, the two right-handed neutrino portal and leptogenesis-friendly fimpzillas

Chianese

J. Cosmol. Astropart. Phys.

2018

“…The relation between these intriguing phenomena has been investigated in many works . One of the interesting possibilities is to connect the dark sector and the Standard Model through the RH neutrinos that realise the type I seesaw, which is usually named the neutrino portal scenario [104][105][106][107][108][109][110][111][112][113][114]. Some recent research [104][105][106] shows that dark matter particles can be dominantly produced through the neutrino Yukawa interactions in the seesaw sector non-thermally by the so-called "freeze-in" mechanism [115,116].…”

Section: Introductionmentioning

confidence: 99%

Dark matter in the type Ib seesaw model

Chianese

2021

J. High Energ. Phys.

We consider a minimal type Ib seesaw model where the effective neutrino mass operator involves two different Higgs doublets, and the two right-handed neutrinos form a heavy Dirac mass. We propose a minimal dark matter extension of this model, in which the Dirac heavy neutrino is coupled to a dark Dirac fermion and a dark complex scalar field, both charged under a discrete Z2 symmetry, where the lighter of the two is a dark matter candidate. Focussing on the fermionic dark matter case, we explore the parameter space of the seesaw Yukawa couplings, the neutrino portal couplings and dark scalar to dark fermion mass ratio, where correct dark matter relic abundance can be produced by the freeze-in mechanism. By considering the mixing between the standard model neutrinos and the heavy neutrino, we build a connection between the dark matter production and current laboratory experiments ranging from collider to lepton flavour violating experiments. For a GeV mass heavy neutrino, the parameters related to dark matter production are constrained by the experimental results directly and can be further tested by future experiments such as SHiP.

“…Another great mystery unanswered by the SM is that of cosmological dark matter (DM), which is commonly thought to be some kind of massive new particle that is stable on cosmological timescales. Although many DM candidates have been proposed, the most common mechanism to account for their stability is to invent a discrete symmetry, the simplest example being Z 2 , under which the dark matter candidate is odd, while the SM particles are even, where such models may be related to neutrino mass and mixing [24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39]. Although this approach can explain the mystery of invisible dark matter, accounting for about a quarter of the energy density of the universe [40], the origin of the discrete symmetry such as Z 2 is rarely considered in the literature, but instead is often just imposed, for example as in the case of R-parity in supersymmetry (SUSY).…”

Section: Introductionmentioning

confidence: 99%

Spontaneously stabilised dark matter from a fermiophobic U(1)′ gauge symmetry

2021

J. High Energ. Phys.

We consider the possibility that dark matter is stabilised by a discrete Z2 symmetry which arises from a subgroup of a U(1)′ gauge symmetry, spontaneously broken by integer charged scalars, and under which the chiral quarks and leptons do not carry any charges. A chiral fermion χ with half-integer charge is odd under the preserved Z2, and hence becomes a stable dark matter candidate, being produced through couplings to right-handed neutrinos with vector-like U(1)′ charges, as in the type Ib seesaw mechanism. We calculate the relic abundance in such a low energy effective seesaw model containing few parameters, then consider a high energy renormalisable model with a complete fourth family of vector-like fermions, where the chiral quark and lepton masses arise from a seesaw-like mechanism. With the inclusion of the fourth family, the lightest vector-like quark can contribute to the dark matter production, enlarging the allowed parameter space that we explore.