Neutrino masses from new seesaw models: Low-scale variants and phenomenological implications

Abstract

With just the Standard Model Higgs doublet, there are only three types of seesaw models that generate light Majorana neutrino masses at tree level after electroweak spontaneous symmetry breaking. However, if there exist additional TeV scalars acquiring vacuum expectation values, coupled with heavier fermionic multiplets, several new seesaw models become possible. These new seesaws are the primary focus of this study and correspond to the tree-level ultraviolet completions of the effective operators studied in a companion publication. We are interested in the genuine cases, in which the standard seesaw contributions are absent. In addition to the tree-level generation of neutrino masses, we also consider the one-loop contributions. Furthermore, we construct low-energy versions that exhibit a very rich phenomenology. Specifically, we scrutinise the generation of dimension-6 operators and explore their implications, including non-unitarity of the leptonic mixing matrix, non-universal $Z-$boson interactions, and lepton flavor violation. Finally, we provide (Generalised) Scotogenic-like variants that incorporate viable dark matter candidates.

30 pages, 6 figures, 9 tables. Submitted with a companion paper; v2: Typos corrected, matches published version

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Cited by in corpus (5)

• Interpretation of 95 GeV Excess within the Georgi-Machacek Model in Light of Positive Definiteness Constraints
• Generalised Casas-Ibarra Parametrisation for Majorana Neutrino Masses
• Triplet fermion WIMP dark matter in the general supersymmetric Georgi-Machacek model
• Investigating the leptonic couplings of doubly charged scalars at the muon collider
• Vacuum Stability Conditions for New $SU(2)$ Multiplets