Taming flavour violation in the Inverse Seesaw

Abstract The Inverse Seesaw mechanism remains one of the most attractive explanations for the lightness of neutrino masses, allowing for natural low-scale realisations. We consider the prospects of a simple extension via 3 generations of sterile fermions — the so called ISS(3) — in what concerns num...

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Main Authors: Jonathan Kriewald, Ana M. Teixeira
Format: Article
Language:English
Published: SpringerOpen 2025-04-01
Series:Journal of High Energy Physics
Subjects:
Online Access:https://doi.org/10.1007/JHEP04(2025)027
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author Jonathan Kriewald
Ana M. Teixeira
author_facet Jonathan Kriewald
Ana M. Teixeira
author_sort Jonathan Kriewald
collection DOAJ
description Abstract The Inverse Seesaw mechanism remains one of the most attractive explanations for the lightness of neutrino masses, allowing for natural low-scale realisations. We consider the prospects of a simple extension via 3 generations of sterile fermions — the so called ISS(3) — in what concerns numerous lepton flavour observables. In order to facilitate a connection between the Lagrangian parameters and low-energy data, we systematically develop new parametrisations of the Yukawa couplings. Relying on these new parametrisations to explore the parameter space, we discuss the complementary role of charged lepton flavour violation searches in dedicated facilities, as well as in lepton colliders (FCC-ee and μTRISTAN). Our results reveal the strong synergy of the different indirect searches in probing the distinct flavour sectors of the model. In particular, we show that in the absence of radiative decays ℓ α → ℓ β γ, sizeable rates for Z-penguin dominated observables could hint at a non-trivially mixed and non-degenerate heavy spectrum.
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spelling doaj-art-936fe27d88074ff8b8d89ef9077d72812025-08-20T03:09:34ZengSpringerOpenJournal of High Energy Physics1029-84792025-04-012025412210.1007/JHEP04(2025)027Taming flavour violation in the Inverse SeesawJonathan Kriewald0Ana M. Teixeira1Jožef Stefan InstitutLaboratoire de Physique de Clermont Auvergne (UMR 6533), CNRS/IN2P3, Université Clermont AuvergneAbstract The Inverse Seesaw mechanism remains one of the most attractive explanations for the lightness of neutrino masses, allowing for natural low-scale realisations. We consider the prospects of a simple extension via 3 generations of sterile fermions — the so called ISS(3) — in what concerns numerous lepton flavour observables. In order to facilitate a connection between the Lagrangian parameters and low-energy data, we systematically develop new parametrisations of the Yukawa couplings. Relying on these new parametrisations to explore the parameter space, we discuss the complementary role of charged lepton flavour violation searches in dedicated facilities, as well as in lepton colliders (FCC-ee and μTRISTAN). Our results reveal the strong synergy of the different indirect searches in probing the distinct flavour sectors of the model. In particular, we show that in the absence of radiative decays ℓ α → ℓ β γ, sizeable rates for Z-penguin dominated observables could hint at a non-trivially mixed and non-degenerate heavy spectrum.https://doi.org/10.1007/JHEP04(2025)027Electroweak Precision PhysicsLepton Flavour Violation (charged)Specific BSM Phenomenology
spellingShingle Jonathan Kriewald
Ana M. Teixeira
Taming flavour violation in the Inverse Seesaw
Journal of High Energy Physics
Electroweak Precision Physics
Lepton Flavour Violation (charged)
Specific BSM Phenomenology
title Taming flavour violation in the Inverse Seesaw
title_full Taming flavour violation in the Inverse Seesaw
title_fullStr Taming flavour violation in the Inverse Seesaw
title_full_unstemmed Taming flavour violation in the Inverse Seesaw
title_short Taming flavour violation in the Inverse Seesaw
title_sort taming flavour violation in the inverse seesaw
topic Electroweak Precision Physics
Lepton Flavour Violation (charged)
Specific BSM Phenomenology
url https://doi.org/10.1007/JHEP04(2025)027
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