A Frequentist analysis of three right-handed neutrinos with GAMBIT

Chrząszcz, M.; Drewes, Marco; Gonzalo, Tomás E.; Harz, Julia; Krishnamurthy, Suraj; Weniger, Christoph

doi:10.1140/epjc/s10052-020-8073-9

Cited by 80 publications

(105 citation statements)

References 168 publications

(301 reference statements)

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“…Modified neutrino couplings to SM gauge bosons have already been considered in the literature in the context of right-handed neutrinos and global fits have also been performed [52,53]. However, extensions with righthanded neutrinos lead necessarily to destructive interference with the SM, whereas here we will also be interested in the most general case allowing for an arbitrary phase of the NP contribution.…”

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confidence: 99%

Global Fit to Modified Neutrino Couplings and the Cabibbo-Angle Anomaly

2020

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Recently, discrepancies of up to 4σ between the different determinations of the Cabibbo angle were observed. In this context, we point out that this "Cabibbo-angle anomaly" can be explained by lepton flavor universality violating new physics in the neutrino sector. However, modified neutrino couplings to standard model gauge bosons also affect many other observables sensitive to lepton flavor universality violation, which have to be taken into account in order to assess the viability of this explanation. Therefore, we perform a model-independent global analysis in a Bayesian approach and find that the tension in the Cabibbo angle is significantly reduced, while the agreement with other data is also mostly improved. In fact, nonzero modifications of electron and muon neutrino couplings are preferred at more than 99.99% C.L. (corresponding to more than 4σ). Still, since constructive effects in the muon sector are necessary, simple models with right-handed neutrinos (whose global fit we update as a by-product) cannot fully explain data, pointing towards more sophisticated new physics models.

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confidence: 99%

Global Fit to Modified Neutrino Couplings and the Cabibbo-Angle Anomaly

2020

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“…GAMBIT has been used for global fits on a wide variety of models, including the scalar singlet dark matter model [7,8], fermion and vector Higgs portal dark matter [9], axions [10], right handed neutrinos [11] and global fits of supersymmetric extensions of the SM [12,13]. Examples of parameter estimation from recent GAMBIT papers are shown in Fig.…”

Section: Gambitmentioning

confidence: 99%

“…In the bottom right results for the Standard Model extended by right-handed neutrinos are shown, taken from Ref. [11]. Further details can be found in the original references.…”

Section: Pos(eps-hep2019)591mentioning

confidence: 99%

New Physics interpretations with GAMBIT

Athron

2020

Proceedings of European Physical Society Conference on High Energy Physics — PoS(EPS-HEP2019)

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I present recent results from the Global and Modular Beyond-the-Standard-Model Inference Tool (GAMBIT) collaboration. Global fits with GAMBIT have been carried out on a variety of models including supersymmetric models, scalar singlet dark matter, fermionic and vector Higgs portal dark matter and axions. Here I focus on a recent GAMBIT study interpreting collider constraints on electroweakinos (arXiv:1809.02097). We show that when the neutralinos and charginos are the only light states of the MSSM, there are scenarios which evade LHC constraints for any mass of the lightest neutralino and the lightest chargino, i.e. the profile likelihood shows no constraint in this plane when one only considers the possibility of excluding new physics. Intriguingly, in addition we also find that excesses in the data can lead to closed confidence level contours, indicating a preference for light neutralinos and charginos over the Standard Model. We find the excess has a local significance of 3.3 sigma when combining ATLAS and CMS 13 TeV searches, but this drops to 2.9 sigma when including 8 TeV searches as well.

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“…Finally, predicting particles at an energy scale within the reach of collider experiments, a selling point of this model is its falsifiability. To guide future experimental efforts, it is thus mandatory to map out the full range of potential observables, especially since it is well known that the inclusion of three right-handed neutrinos can significantly change the JHEP01(2021)200 experimentally viable parameter space [7], cosmological constraints [8], and the perspectives for leptogenesis [9]. In this work we study a comparably unexplored region of parameter space in which all heavy neutrinos have masses below the pion mass, kinematically limiting their decay products to SM neutrinos, electrons, positrons, and photons.…”

Section: Introductionmentioning

confidence: 99%

MeV-scale seesaw and leptogenesis

Domcke

Drewes

Hufnagel

et al. 2021

J. High Energ. Phys.

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We study the type-I seesaw model with three right-handed neutrinos and Majorana masses below the pion mass. In this mass range, the model parameter space is not only strongly constrained by the requirement to explain the light neutrino masses, but also by experimental searches and cosmological considerations. In the existing literature, three disjoint regions of potentially viable parameter space have been identified. In one of them, all heavy neutrinos decay shortly before big bang nucleosynthesis. In the other two regions, one of the heavy neutrinos either decays between BBN and the CMB decoupling or is quasi-stable. We show that previously unaccounted constraints from photodisintegration of nuclei practically rule out all relevant decays that happen between BBN and the CMB decoupling. Quite remarkably, if all heavy neutrinos decay before BBN, the baryon asymmetry of the universe can be quite generically explained by low-scale leptogenesis, i.e. without further tuning in addition to what is needed to avoid experimental and cosmological constraints. This motivates searches for heavy neutrinos in pion decay experiments.

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A Frequentist analysis of three right-handed neutrinos with GAMBIT

Cited by 80 publications

References 168 publications

Global Fit to Modified Neutrino Couplings and the Cabibbo-Angle Anomaly

Global Fit to Modified Neutrino Couplings and the Cabibbo-Angle Anomaly

New Physics interpretations with GAMBIT

MeV-scale seesaw and leptogenesis

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