Radiative neutrino masses and successful S U ( 5 ) unification

If a grand-unified extension of the asymptotically safe Reuter fixed-point for quantum gravity exists, it determines free parameters of the grand-unified scalar potential. All quartic couplings take their fixed-point values in the trans-Planckian regime. They are irrelevant parameters that are, in principle, computable for a given particle content of the grand unified model. In turn, the direction of spontaneous breaking of the grand-unified gauge symmetry becomes predictable. For the flow of the couplings below the Planck mass, gauge and Yukawa interactions compete for the determination of the minimum of the effective potential.

Section: Jhep08(2020)111mentioning

confidence: 99%

Predictive power of grand unification from quantum gravity

Eichhorn

Held

Wetterich

2020

“…The model realizes operator O 4 8 of Table V. assuming two copies of the χ field, namely, χ 1 and χ 2 , one could restore this coupling from χ 1 χ 2 ∆, in which case the diagram of Fig. 44 can be connected [41]. The NSI in such a model is identical to the model described in this section.…”

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confidence: 90%

“…7.1.5. In this up-quark variant, one could replace the diquark ∆ 6, 1, 4 3 by a color triplet field ∆ 3, 1, 4 3 as well [41].…”

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confidence: 99%

Non-standard interactions in radiative neutrino mass models

Babu

Dev

Jana

et al. 2020

136

126

Models of radiative Majorana neutrino masses require new scalars and/or fermions to induce lepton number violating interactions. We show that these new particles also generate observable neutrino nonstandard interactions (NSI) with matter. We classify radiative models as type-I or II, with type-I models containing at least one Standard Model (SM) particle inside the loop diagram generating neutrino mass, and type-II models having no SM particle inside the loop. While type-II radiative models do not generate NSI at tree-level, popular models which fall under the type-I category are shown, somewhat surprisingly, to generate observable NSI at tree-level, while being consistent with direct and indirect constraints from colliders, electroweak precision data and charged-lepton flavor violation (cLFV). We survey such models where neutrino masses arise at one, two and three loops. In the prototypical Zee model which generates neutrino masses via one-loop diagrams involving charged scalars, we find that diagonal NSI can be as large as (8%, 3.8%, 9.3%) for (ε ee , ε µµ , ε τ τ ), while off-diagonal NSI can be at most (1.5 × 10 −3 %, 0.56%, 0.34%) for (ε eµ , ε eτ , ε µτ ). In one-loop neutrino mass models using leptoquarks (LQs), (ε µµ , ε τ τ ) can be as large as (21.6%, 51.7%), while ε ee and (ε eµ , ε eτ , ε µτ ) can at most be 0.6%. Other twoand three-loop LQ models are found to give NSI of similar strength. The most stringent constraints on the diagonal NSI are found to come from neutrino oscillation and scattering experiments, while the off-diagonal NSI are mostly constrained by low-energy processes, such as atomic parity violation and cLFV. We also comment on the future sensitivity of these radiative models in long-baseline neutrino experiments, such as DUNE. While our analysis is focused on radiative neutrino mass models, it essentially covers all NSI possibilities with heavy mediators. arXiv:1907.09498v2 [hep-ph] 3 Oct 2019 Contents 7 Other type-I radiative models 76 7.1 One-loop models 77 7.1.1 Minimal radiative inverse seesaw model 77 7.1.2 One-loop model with vectorlike leptons 80 7.1.3 SU (2) L -singlet leptoquark model with vectorlike quark 82 7.1.4 SU (2) L -doublet leptoquark model with vectorlike quark 83 7.1.5 Model with SU (2) L -triplet leptoquark and vectorlike quark 84 7.1.6 A new extended one-loop leptoquark model 85 7.2 Two-loop models 87 7.2.1 Zee-Babu model 87 7.2.2 Leptoquark/diquark variant of the Zee-Babu model 88 7.2.3 Model with SU (2) L -doublet and singlet leptoquarks 89 7.2.4 Leptoquark model with SU (2) L -singlet vectorlike quark 90 7.2.5 Angelic model 91 7.2.6 Model with singlet scalar and vectorlike quark 92 7.2.7 Leptoquark model with vectorlike lepton 93 7.2.8 Leptoquark model with SU (2) L -doublet vectorlike quark 93 7.2.9 A new two-loop leptoquark model 94 7.3 Three-loop models 95 7.3.1 KNT Model 95 7.3.2 AKS model 96 7.3.3 Cocktail Model 97 7.3.4 Leptoquark variant of the KNT model 98 -ii -7.3.5 SU (2) L -singlet three-loop model 99 7.4 Four-and higher-loop models 100 8 Type II r...

“…[35] based on the number of exotic degrees of freedom by which the SM is extended. There, the method is applied to the case of radiative models with two exotics, 2 and has also been used to study minimal neutrino-mass models compatible with SU(5) unification [36].…”

Section: Jhep01(2021)074mentioning

confidence: 99%

Exploding operators for Majorana neutrino masses and beyond

Gargalionis

Volkas

2021

Building UV completions of lepton-number-violating effective operators has proved to be a useful way of studying and classifying models of Majorana neutrino mass. In this paper we describe and implement an algorithm that systematises this model-building procedure. We use the algorithm to generate computational representations of all of the tree-level completions of the operators up to and including mass-dimension 11. Almost all of these correspond to models of radiative neutrino mass. Our work includes operators involving derivatives, updated estimates for the bounds on the new-physics scale associated with each operator, an analysis of various features of the models, and a look at some examples. We find that a number of operators do not admit any completions not also generating lower-dimensional operators or larger contributions to the neutrino mass, ruling them out as playing a dominant role in the neutrino-mass generation. Additionally, we show that there are at most five models containing three or fewer exotic multiplets that predict new physics that must lie below 100 TeV. Accompanying this work we also make available a searchable database containing all of our results and the code used to find the completions. We emphasise that our methods extend beyond the study of neutrino-mass models, and may be useful for generating completions of high-dimensional operators in other effective field theories. Example code: ref. [37].