New Weinberg operator for neutrino mass and its seesaw origin

Hernández-García, Josu; King, Stephen F.

doi:10.1007/jhep05(2019)169

Cited by 19 publications

(37 citation statements)

References 69 publications

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“…For flavour models with finite modular symmetry outlined above, only one single modulus field τ is usually included, corresponding to a single finite modular group symmetry Γ N . 3 An alternative type-Ib seesaw mechanism, yielding the new Weinberg operators H uHd L i L j withH d being a charge conjugated second Higgs doublet with opposite hypercharge, was proposed in [8] recently. 4 We apply the standard convention of the S 4 generators S, T , and U where S 2 = T 3 = U 2 = (ST ) 3 = (SU ) 2 = (T U ) 2 = I [9] hold.…”

Section: Introductionmentioning

confidence: 99%

Trimaximal TM1 mixing with two modular S4 groups

2020

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We discuss a minimal flavon-free model with twin modular symmetries, leading to trimaximal TM 1 lepton mixing in which the first column of the tri-bimaximal lepton mixing matrix is preserved. The model involves two modular S 4 groups, one acting in the neutrino sector, associated with a modulus field value τ SU with residual Z SU 2 symmetry, and one acting in the charged lepton sector, associated with a modulus field value τ T with residual Z T 3 symmetry. Apart from the predictions of TM 1 mixing, the model leads to a new neutrino mass sum rule which implies lower bounds on neutrino masses close to current limits from neutrinoless double beta decay experiments and cosmology.

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Section: Introductionmentioning

confidence: 99%

Trimaximal TM1 mixing with two modular S4 groups

2020

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“…The new effective dimension 5 operator is mediated by the Dirac KK neutrino modes, as shown in figure 3. In fact this version of the type Ib seesaw mechanism is slightly different to that proposed in [25], since it involves two additional scalar singlets φφ † , leading to additional mass suppression, but the basic features are the same: two different Higgs doublets with a single Dirac heavy neutrino mass mediating the diagram, leading to light effective Majorana neutrino masses. However, assuming zero 5d Dirac masses, the new mechanism does not so far explain the smallness of neutrino mass unless the compactification scale is quite high, or at least one of the Yukawa couplings is very small.…”

Section: Neutrino Majorana Masses From Kk Dirac Neutrinosmentioning

confidence: 90%

“…The origin of neutrino masses in this set-up is also quite interesting since the usual type I seesaw mechanism cannot be implemented due to the absence of Majorana masses in 5d. Instead we shall rely on the recently proposed type Ib seesaw mechanism [25], where heavy Dirac KK neutrino masses can yield small physical Majorana neutrino masses.…”

Section: Jhep03(2021)078mentioning

confidence: 99%

“…Note that this is not the usual Weinberg operator since it involves two different Higgs doublets, so it is a new type of Weinberg operator, originating from a variant of the type I see saw mechanism called the type Ib seesaw mechanism [25]. The new effective dimension 5 operator is mediated by the Dirac KK neutrino modes, as shown in figure 3.…”

Section: Neutrino Majorana Masses From Kk Dirac Neutrinosmentioning

confidence: 99%

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Quark and lepton mass and mixing with non-universal Z′ from a 5d Standard Model with gauged SO(3)

Anda

King

2021

J. High Energ. Phys.

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We propose a theory of quark and lepton mass and mixing with non-universal Z′ couplings based on a 5d Standard Model with quarks and leptons transforming as triplets under a new gauged SO(3) isospin. In the 4d effective theory, the SO(3) isospin is broken to U(1)′, through a S1/(ℤ2×$$ {\mathrm{\mathbb{Z}}}_2^t $$ ℤ 2 t ) orbifold, then subsequently dynamically broken, resulting in a massive Z′. Quarks and leptons in the 5d bulk appear as massless modes, with zero Yukawa couplings to the Higgs on the brane, and zero couplings to Z′, at leading order, due to the U(1)′ symmetry. However, after the U(1)′ breaking, both Yukawa couplings and non-universal Z′ couplings are generated by heavy Kaluza-Klein exchanges. Hierarchical quark and lepton masses result from a hierarchy of 5d Dirac fermion masses. Neutrino mass and mixing arises from a novel type Ib seesaw mechanism, mediated by Kaluza-Klein Dirac neutrinos. The non-universal Z′ couplings may contribute to semi-leptonic B decay ratios which violate μ − e universality. In this model such couplings are related to the corresponding quark and lepton effective Yukawa couplings.

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“…Recently a new version of the type I seesaw mechanism has been proposed called the type Ib seesaw mechanism [21] which may be just as testable as the low scale seesaw models above while allowing just two right-handed neutrinos [22]. It had been pointed out a long time ago that the traditional Weinberg operator is not the only pathway to neutrino mass in models with multiple Higgs doublets [23].…”

Section: Introductionmentioning

confidence: 99%

Dark matter in the type Ib seesaw model

Chianese

King

2021

J. High Energ. Phys.

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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.

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New Weinberg operator for neutrino mass and its seesaw origin

Cited by 19 publications

References 69 publications

Trimaximal TM1 mixing with two modular S4 groups

Trimaximal TM1 mixing with two modular S4 groups

Quark and lepton mass and mixing with non-universal Z′ from a 5d Standard Model with gauged SO(3)

Dark matter in the type Ib seesaw model

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