Modular S4 Inverse Seesaw at the LZ High-Recoil Frontier
Abstract
The extension of the LUX--ZEPLIN nuclear-recoil analysis to approximately 270 keV probes a qualitatively new dark-matter regime in which endothermic scattering can suppress conventional low-energy recoils and concentrate the surviving spectrum near the Galactic high-velocity tail. We construct a modular-S4 realization in which a minimal 2NR+2S inverse seesaw accounts for lepton flavor, while a separate pair of Standard-Model-singlet fermions forms the pseudo-Dirac state relevant for high-recoil xenon scattering. The sectors share a common complex modulus τ, so the modular forms selected by charged-lepton and neutrino data also enter the operators generating the dark Dirac mass and Majorana splitting. Our scan yields $181447$ lepton-sector solutions satisfying χ2ℓ+ν<30, distributed among several disconnected modular regions, and predicts one effectively massless light neutrino at leading order. Restoring the physical scales allows TeV-scale heavy quasi-Dirac neutral fermions with small non-unitarity. We subsequently scan 2×106 dark-sector points only over flavor-accepted values of τ and identify common-modulus solutions in the LZ-oriented region 300 GeV≤ mχ≤2 TeV and 300 keV≤δ≤400 keV. An exploratory two-bin Poisson likelihood, including endothermic xenon kinematics, the Helm form factor, Standard-Halo-Model velocities, Gaussian energy smearing, and profiling over the signal normalization, gives a best grid point at (mχ,δ)≃(1.847 TeV,371.5 keV), close to the terrestrial inelastic kinematic ceiling. The construction provides a direct link between modular lepton flavor, TeV-scale inverse-seesaw dynamics, and high-recoil inelastic dark matter.
Related
- Inelastic Self-interacting Dark Matter and LUX-ZEPLIN 248 keV Event in a Dirac Modular Inverse Seesaw
- Probing the dynamical inverse seesaw mechanism with low-frequency gravitational waves
- (g−2)ℓ and LFV decays in a U(1)Lμ −Lτ left-right model with inverse seesaw neutrinos
- Testable neutrino mass and TeV-scale leptogenesis in a D4 inverse seesaw model
- Leptogenesis and dark matter in an inverse Seesaw from gauged B − L breaking
BibTeX
@misc{ahmed2026modular,
title = {{Modular $S_4$ Inverse Seesaw at the LZ High-Recoil Frontier}},
author = {Waqas Ahmed and Vasileios Basiouris and George K. Leontaris},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.15557},
eprint = {2610.15557},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.15557},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Modular S_4 Inverse Seesaw at the LZ High-Recoil Frontier
AU - Waqas Ahmed
AU - Vasileios Basiouris
AU - George K. Leontaris
PY - 2026
DA - 2026/10/11
PB - arXiv
DO - 10.48550/arxiv.2610.15557
UR - https://arxiv.org/abs/2610.15557
AB - The extension of the LUX--ZEPLIN nuclear-recoil analysis to approximately 270 keV probes a qualitatively new dark-matter regime in which endothermic scattering can suppress conventional low-energy recoils and concentrate the surviving spectrum near the Galactic high-velocity tail. We construct a modular-S_4 realization in which a minimal 2N_R+2S inverse seesaw accounts for lepton flavor, while a separate pair of Standard-Model-singlet fermions forms the pseudo-Dirac state relevant for high-recoil xenon scattering. The sectors share a common complex modulus τ, so the modular forms selected by charged-lepton and neutrino data also enter the operators generating the dark Dirac mass and Majorana splitting. Our scan yields $181447$ lepton-sector solutions satisfying χ^2_ℓ+ν<30, distributed among several disconnected modular regions, and predicts one effectively massless light neutrino at leading order. Restoring the physical scales allows TeV-scale heavy quasi-Dirac neutral fermions with small non-unitarity. We subsequently scan 2×10^6 dark-sector points only over flavor-accepted values of τ and identify common-modulus solutions in the LZ-oriented region 300 GeV≤ m_χ≤2 TeV and 300 keV≤δ≤400 keV. An exploratory two-bin Poisson likelihood, including endothermic xenon kinematics, the Helm form factor, Standard-Halo-Model velocities, Gaussian energy smearing, and profiling over the signal normalization, gives a best grid point at (m_χ,δ)≃(1.847 TeV,371.5 keV), close to the terrestrial inelastic kinematic ceiling. The construction provides a direct link between modular lepton flavor, TeV-scale inverse-seesaw dynamics, and high-recoil inelastic dark matter.
ER -