The Dark Dimension and Majorana Neutrinos
Abstract
Recent developments in the Swampland program motivate the existence of a mesoscopic Dark Dimension of size 0.1−10 μm with bulk Majorana fermions in the 1−10 keV range. Motivated by this, we derive terrestrial constraints on Majorana bulk neutrinos as a function of the compactification radius. After determining the mass spectrum and mixing structure, we confront the model with Daya Bay neutrino-oscillation data, the KATRIN beta-decay bound, and the KamLAND-Zen neutrinoless double beta decay limit. For the latter, we obtain a closed-form expression for the effective Majorana mass and show that the Kaluza-Klein tower efficiently screens neutrinoless double beta decay when the nuclear momentum exceeds the compactification and Majorana scales. In the Dark-Dimension window, beta decay provides the strongest constraint, pushing the allowed Yukawa couplings down to 𝒪(10−3). Oscillation and neutrinoless double beta decay searches remain complementary, probing smaller and larger Majorana masses, respectively. For completeness, outside the Dark-Dimension assumptions, we investigate how hierarchical Majorana masses can weaken the constraints.
Related
- Cosmology & Astrophysics of the Dark Dimension with Bulk Majorana Neutrinos
- Exploring R˜2 leptoquarks and Majorana neutrinos via same-sign dimuons at the HL-LHC
- Are neutrinos Majorana? Fixed-target and high-energy astrophysical searches decide
- Low-Scale See-Saw Mechanism and the Majorana Nature of Heavy Neutrinos
- Probing TeV-scale Majorana neutrinos at a muon-proton collider via a lepton-number-violating fat-jet signature
BibTeX
@misc{giorgi2026dark,
title = {{The Dark Dimension and Majorana Neutrinos}},
author = {Arturo de Giorgi and Dhruv Pasari},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.10668},
eprint = {2609.10668},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.10668},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - The Dark Dimension and Majorana Neutrinos
AU - Arturo de Giorgi
AU - Dhruv Pasari
PY - 2026
DA - 2026/09/09
PB - arXiv
DO - 10.48550/arxiv.2609.10668
UR - https://arxiv.org/abs/2609.10668
AB - Recent developments in the Swampland program motivate the existence of a mesoscopic Dark Dimension of size 0.1−10 μm with bulk Majorana fermions in the 1−10 keV range. Motivated by this, we derive terrestrial constraints on Majorana bulk neutrinos as a function of the compactification radius. After determining the mass spectrum and mixing structure, we confront the model with Daya Bay neutrino-oscillation data, the KATRIN beta-decay bound, and the KamLAND-Zen neutrinoless double beta decay limit. For the latter, we obtain a closed-form expression for the effective Majorana mass and show that the Kaluza-Klein tower efficiently screens neutrinoless double beta decay when the nuclear momentum exceeds the compactification and Majorana scales. In the Dark-Dimension window, beta decay provides the strongest constraint, pushing the allowed Yukawa couplings down to 𝒪(10^−3). Oscillation and neutrinoless double beta decay searches remain complementary, probing smaller and larger Majorana masses, respectively. For completeness, outside the Dark-Dimension assumptions, we investigate how hierarchical Majorana masses can weaken the constraints.
ER -