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Scotogenic Neutrino Mass Generation Models

M. F. América Noemí Morales Anda

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The Standard Model (SM)

Gauge symmetry:

SU (3)×SU (2)×U (1)

19 parameters

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Beyond the SM

Some non solving problems in the SM:

Nature of Dark Matter (DM)
Neutrino mass
Neutrino nature.

𝞶 = anti(𝞶) 𝞶 ≠ anti(𝞶)

¿?

0νββ process

Strong CP problem
Baryon asymmetry
etc.

However, there are some physical phenomena in nature that the Standard Model does not explain, for example:

Nature of Dark Matter (DM): The standard model explains about 5% of the energy present in the universe. About 26% should be dark matter.Yet, the SM does not supply any fundamental particles that are good dark matter candidates.
Neutrino mass and nature: An important question its about the nature of neutrinos, are or aren’t their own antiparticle?

Furthermore, if neutrinos are Majorana, the dynamical equation will not be the Dirac equation any more. Thus, changing our model where all fermions can be described as Dirac spinors.

The most sensitive way to investigate the Dirac or Majorana nature of the neutrino is neutrinoless double beta decay (DBD).

Experiments like NEMO 3 ( installed in France) and Cuore (in Italy) are made to observe DBD processes.

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Neutrinos.

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Neutrino Mass Models

Some models of neutrino mass generation:

Seesaw Mechanism

Type l

Type ll

Type lll

Scotogenic Model

Scoto 3311

Scoto B-L

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The Seesaw Mechanism

In the Type-I seesaw the neutrino mass is induced from the fermion exchange, while Type-II corresponds to scalar boson exchange.

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The Scotogenic Model

Scotogenic

(physics) Created from dark matter

The Model:

Minimal extension to SM : SU(2)_L × U(1)_Y× Z₂
Tree-level neutrino masses are not possible, but a loop-level Majorana mass can still occur.
Two candidates for the dark matter

Ma, Phys. Rev. D 73, 077301 (2006)

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Particle content of the Scotogenic Model:

Neutrino Mass term:

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Extensions of the Scotogenic Model : Scotogenic 3-3-1-1

Scotogenic 3-3-1-1

Julio Leite, América Morales, José W. F. Valle,Carlos A.Vaquera-Araujo (2020)

arXiv:2005.03600 [hep-ph]

SU(3)_C ⊗ SU(3)_L ⊗ U(1)_X ⊗ U(1)_N gauge symmetry as a minimal extension of SVS 3-3-1 model (Phys. Rev. D22 (1980) 738).

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Our model contains four triplet scalars, three of them are Higgs-like, even under matter parity, while Φ_4 is “dark” or M_P odd.

The resulting scalar potential is given by

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Model Phenomenology

Fig. Constraints on the dark matter mass 𝜂₁. The red shaded region is ruled out by direct detection experiments, XENON1T and LUX .

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Extension of the Scotogenic Model: Scotogenic B-L

Scotogenic B-L

Julio Leite, América Morales, José W. F. Valle,Carlos A.Vaquera-Araujo (2020)

arXiv:2003.02950 [hep-ph]

Promotion of B-L to a local symmetry.

The unbroken B − L is responsible for:

Dirac nature of the neutrino mass
Stabilisation of a dark matter candidate.

We proposed another interesting scenario where we consider the case of gauged unbroken B − L as the dark matter stabilisation symmetry.

In order to promote the accidental B − L global symmetry of the standard model to a local one, we need to extend the standard model field content to ensure anomaly cancellation. Then the inclusion of three right-handed neutrinos ν _i R with B − L charge of − 1 , is enough to make it anomaly free and hence consistent.

We propose alternative ways of generating small neutrino masses, relying neither on unnaturally suppressed Yukawa couplings nor on inaccessibly large energy scales.

We suggest two standard model extensions with gauged B − L and dark matter as the mediator of neutrino mass generation.

In Model A, we add a new doublet η and a singlet σ in the scalar sector, both charged under the B − L symmetry. In the fermion sector, three right-handed neutrinos, ν i R , as well as three gauge singlet fermions, S i R , are introduced.

We also propose a variant, Model B, shown in Table 3. This differs from Model A due to introduction of three extra fermion fields: S_L

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Yukawa Lagrangians for models A and B, respectively

In both cases the neutrino masses have the same form

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Scotogenic B-L neutrino masses

If the lightest M_P odd is stable and electrically neutral.

DM candidate.

Complex neutral scalar.

Fermionic

Majorana.
Dirac

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Conclusions

We need neutrino mass generation models to solve some of the standard model problems.

A specially attractive possibility is that neutrino mass and dark matter have a common origin: Scotogenic Model.

Unbroken B − L local symmetry is responsible for both the Dirac nature of the neutrino mass and the stabilisation of a dark matter candidate.

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Conclusions

We need neutrino mass generation models to solve some of the standard model problems.

A specially attractive possibility is that neutrino mass and dark matter have a common origin: Scotogenic Model.

Scotogenic extension of the SVS 3-3-1 model. Conservation of B − L gauge symmetry in the SU(3) c ⊗ SU(3) L ⊗ U(1) X ⊗ U(1) N theory ensures the stability of dark matter, linked to the Dirac nature of neutrinos.

Unbroken B − L local symmetry is responsible for both the Dirac nature of the neutrino mass and the stabilisation of a dark matter candidate.

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Thanks