Constraining the minimal type-III seesaw model with naturalness, lepton flavor violation, and electroweak vacuum stability

Goswami, Sumanta; Vishnudath, K. N.; Khan, Najimuddin

doi:10.1103/physrevd.99.075012

Cited by 30 publications

(35 citation statements)

References 101 publications

(135 reference statements)

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“…[15,16,17,18,19], neutrino mass generation and vacuum stability in Refs. [20,21,22,23,24,25], universal extra dimension model in Ref. [26], SM extensions with an additional U (1) gauge symmetry in Refs.…”

Section: Introductionmentioning

confidence: 99%

Higgs vacuum stability with vectorlike fermions

Gopalakrishna

Velusamy

2019

Phys. Rev. D

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We present the effects of vector-like fermions (VLF) on the stability of the Higgs electroweak vacuum, using the renormalization group improved Higgs effective potential. We review the calculation of the one-loop beta-functions of the standard model couplings paying particular attention to the fermion contributions. From this, we derive the VLF contributions to the betafunctions. We also include the significant two-loop contributions to the beta-functions. Using these beta-functions, we determine the scale at which the effective Higgs quartic-coupling becomes zero and goes negative, signaling vacuum instability. We find that for certain VLF masses and Yukawa couplings, the Higgs quartic stays positive for field values all the way up to the Planck scale, implying that the meta-stable vacuum of the standard model can be rendered absolutely stable if VLFs are present with certain parameters. For other values of VLF parameters, the Higgs vacuum is metastable as in the standard model. For cases where the vacuum is metastable, we compute the probability of quantum tunneling from the false electroweak vacuum into a deeper true vacuum in our Hubble volume by numerically solving for the bounce configuration in Euclidean space-time and computing the bounce action for it. We compare our numerical solution with the analytical approximation for the bounce action commonly used in the literature, and comment on when the latter may be used. * shri@imsc.res.in † arunprasath@imsc.res.in arXiv:1812.11303v3 [hep-ph] 13 Jul 2019Denoting the field value as h ≡ µ and denoting λ eff (µ) as just λ(µ), it can be shown (see for example Ref. [41]) that λ(µ) obeys a renormalization group equation (RGE) of the formThe RGE is interpreted now as an evolution with field value h = µ, and the β-function β λ is the usual β-function for the coupling λ, governed by the RGE. The λ(µ) obtained by integrating the RGE has the leading logs of the form log n (µ/M ) resummed. β λ is shown as a function of λ itself, and also of the other couplings that contribute significantly, which, in the SM, are the top Yukawa coupling y t and the SU (3), SU (2), U (1) gauge couplings g a = {g 3 , g 2 , g 1 }. All these couplings also evolve with µ via analogous RGE equations with their corresponding β-functions β yt , β ga . We neglect the contributions of the other SM couplings to the β-functions as they contribute insignificantly. From Eq.(3) we see that for h m h , the instability is signalled by the Higgs quartic effective coupling λ(µ) becoming negative.As we show explicitly later, β λ obtains a negative contribution from y t , while it obtains a positive contribution from λ(µ) itself and from gauge couplings. Thus, the top quark has the important effect of decreasing λ(µ), and for y t as large as in the SM, for the observed m h , it drives λ(µ) negative at higher energies, signaling vacuum instability. The effect of fermions coupled to the Higgs is generally to destabilize the electroweak vacuum, although in this work we show that this statement is not so definit...

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Section: Introductionmentioning

confidence: 99%

Higgs vacuum stability with vectorlike fermions

Gopalakrishna

Velusamy

2019

Phys. Rev. D

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“…To demonstrate the feature of such cases, we have considered a specific example, where the SM is extended by an SU(2) L real triplet fermion Σ = (Σ 1 , Σ 2 , Σ 3 ). This additional DOF plays a central role in the generation of neutrino masses and mixing [87,[94][95][96][97][98][99][100], lepton flavour violating decays [101][102][103][104][105][106][107], explaining dark matter [108][109][110][111], and CP & matter-antimatter asymmetry [112][113][114][115]. In most of these scenarios, this JHEP01(2021)028 triplet fermion is accompanied by other particles which can be integrated out to construct an effective Lagrangian described by SM DOFs and Σ.…”

Section: Sm + Left-handed Triplet Fermion (σ)mentioning

confidence: 99%

Effective operator bases for beyond Standard Model scenarios: an EFT compendium for discoveries

Banerjee

Chakrabortty

Prakash

et al. 2021

J. High Energ. Phys.

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It is not only conceivable but likely that the spectrum of physics beyond the Standard Model (SM) is non-degenerate. The lightest non-SM particle may reside close enough to the electroweak scale that it can be kinematically probed at high-energy experiments and on account of this, it must be included as an infrared (IR) degree of freedom (DOF) along with the SM ones. The rest of the non-SM particles are heavy enough to be directly experimentally inaccessible and can be integrated out. Now, to capture the effects of the complete theory, one must take into account the higher dimensional operators constituted of the SM DOFs and the minimal extension. This construction, BSMEFT, is in the same spirit as SMEFT but now with extra IR DOFs. Constructing a BSMEFT is in general the first step after establishing experimental evidence for a new particle. We have investigated three different scenarios where the SM is extended by additional (i) uncolored, (ii) colored particles, and (iii) abelian gauge symmetries. For each such scenario, we have included the most-anticipated and phenomenologically motivated models to demonstrate the concept of BSMEFT. In this paper, we have provided the full EFT Lagrangian for each such model up to mass dimension 6. We have also identified the CP, baryon (B), and lepton (L) number violating effective operators.

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“…In this section, we discuss the extended fermionic sectors of the models and present bounds on the model parameters. The Lagrangians that are relevant to neutrino mass generation are [7]…”

Section: Type-iii Seesaw Model and Present Boundsmentioning

confidence: 99%

“…In this work, the minimal Type-III seesaw model is proposed in which the SM is extended by adding two hyperchargeless SU (2) L triplet fermions to explain the origin of the non-zero neutrino masses and U P M N S mixing [7]. In this scenario, the lightest active neutrino will be massless.…”

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confidence: 99%

Constraints on Minimal Type-III Seesaw Model from Naturalness, Lepton Flavor Violation, and Electroweak Vacuum Stability

Goswami

Vishnudath

Khan

2021

Springer Proceedings in Physics

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We study the minimal Type-III seesaw model to explain the origin of the non-zero neutrino masses and mixing. We show that the naturalness arguments and the bounds from lepton flavor violating decay (μ → eγ ) provide very stringent bounds on the model along with the constraints on the stability of the electroweak vacuum up to high energy scale. We perform a detailed analysis of the model parameter space including all the constraints for both normal and inverted hierarchies of the light neutrino masses. We find that most of the regions that are allowed by naturalness and lepton flavor violating decay fall into the metastable region.

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Constraining the minimal type-III seesaw model with naturalness, lepton flavor violation, and electroweak vacuum stability

Cited by 30 publications

References 101 publications

Higgs vacuum stability with vectorlike fermions

Higgs vacuum stability with vectorlike fermions

Effective operator bases for beyond Standard Model scenarios: an EFT compendium for discoveries

Constraints on Minimal Type-III Seesaw Model from Naturalness, Lepton Flavor Violation, and Electroweak Vacuum Stability

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