Heavy Sterile Fermions from the Atmosphere: LZ Limits on Neutrino Up-Scattering
Abstract
The LUX-ZEPLIN (LZ) experiment has recently reported data extending to nuclear-recoil energies of about 270 keV, including a single event at 248 keV in a nearly background-free region, for an exposure of 2.84 tonne-years. We examine this dataset through neutrino up-scattering to a heavy sterile fermion induced by atmospheric neutrinos, mediated by vector, axial-vector, scalar and dipole interactions. Our main result is a set of constraints: using the part of the LZ data where no excess is observed, we obtain new bounds on all four scenarios that probe regions of parameter space not tested before, and show that dark matter detectors can provide competitive limits on neutrino up-scattering for sterile fermion masses above ∼ 50 MeV. We also test whether the 248~keV event can be explained in this way while remaining consistent with the absence of events at lower recoil energies. For the scalar, vector and axial mediators this requires couplings at the edge of perturbativity, while the dipole does not provide a good fit, so we conclude that up-scattering is not a compelling explanation of the event.
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BibTeX
@misc{sierra2026heavy,
title = {{Heavy Sterile Fermions from the Atmosphere: LZ Limits on Neutrino Up-Scattering}},
author = {D. Aristizabal Sierra and V. De Romeri and D. K. Papoulias and I. M. Shoemaker},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.32747},
eprint = {2610.32747},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.32747},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Heavy Sterile Fermions from the Atmosphere: LZ Limits on Neutrino Up-Scattering
AU - D. Aristizabal Sierra
AU - V. De Romeri
AU - D. K. Papoulias
AU - I. M. Shoemaker
PY - 2026
DA - 2026/10/23
PB - arXiv
DO - 10.48550/arxiv.2610.32747
UR - https://arxiv.org/abs/2610.32747
AB - The LUX-ZEPLIN (LZ) experiment has recently reported data extending to nuclear-recoil energies of about 270 keV, including a single event at 248 keV in a nearly background-free region, for an exposure of 2.84 tonne-years. We examine this dataset through neutrino up-scattering to a heavy sterile fermion induced by atmospheric neutrinos, mediated by vector, axial-vector, scalar and dipole interactions. Our main result is a set of constraints: using the part of the LZ data where no excess is observed, we obtain new bounds on all four scenarios that probe regions of parameter space not tested before, and show that dark matter detectors can provide competitive limits on neutrino up-scattering for sterile fermion masses above ∼ 50 MeV. We also test whether the 248~keV event can be explained in this way while remaining consistent with the absence of events at lower recoil energies. For the scalar, vector and axial mediators this requires couplings at the edge of perturbativity, while the dipole does not provide a good fit, so we conclude that up-scattering is not a compelling explanation of the event.
ER -