A Vector-Like Lepton Interpretation of the High-Energy Nuclear Recoil Candidate in LUX-ZEPLIN
- 1PRISMA ++ Cluster of Excellence & Mainz Institute for Theoretical Physics , Johannes Gutenberg University , 55099 Mainz , Germany
Abstract
The LUX-ZEPLIN (LZ) experiment has recently reported a nuclear-recoil candidate at ER=248±23stat±23sys keV in an exposure of 2.84 tonne yr. At this unusually high recoil energy, the spin-independent (SI) xenon response is strongly suppressed, motivating dark matter interactions with a harder recoil spectrum. We show that elastic spin-dependent (SD) scattering through the nonrelativistic operator 𝒪4=SDM·SN provides a simple realization of such a spectrum. We consider singlet-doublet Majorana dark matter, for which a diagonal Z coupling generates the required SD interaction. The accompanying Higgs-mediated SI interaction would generically produce too many low-energy recoils, but can be suppressed along a Higgs blind spot while retaining a nonzero Z coupling. We find a region of the Higgs blind spot that simultaneously predicts an 𝒪(1) event rate in the LZ high-recoil window and reproduces the observed thermal relic abundance. The same SD interaction leads to solar capture, allowing this region to be tested independently with solar-neutrino searches. Current IceCube limits already probe part of the LZ-compatible thermal parameter space, while a viable region remains. Additional xenon exposure and improved solar-neutrino searches can therefore provide complementary tests of this interpretation.
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BibTeX
@misc{elahi2026vectorlike,
title = {{A Vector-Like Lepton Interpretation of the High-Energy Nuclear Recoil Candidate in LUX-ZEPLIN}},
author = {Fatemeh Elahi and Pedro Schwaller},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.08993},
eprint = {2609.08993},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.08993},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - A Vector-Like Lepton Interpretation of the High-Energy Nuclear Recoil Candidate in LUX-ZEPLIN
AU - Fatemeh Elahi
AU - Pedro Schwaller
PY - 2026
DA - 2026/09/08
PB - arXiv
DO - 10.48550/arxiv.2609.08993
UR - https://arxiv.org/abs/2609.08993
AB - The LUX-ZEPLIN (LZ) experiment has recently reported a nuclear-recoil candidate at E_R=248±23_stat±23_sys keV in an exposure of 2.84 tonne yr. At this unusually high recoil energy, the spin-independent (SI) xenon response is strongly suppressed, motivating dark matter interactions with a harder recoil spectrum. We show that elastic spin-dependent (SD) scattering through the nonrelativistic operator 𝒪_4=S_DM·S_N provides a simple realization of such a spectrum. We consider singlet-doublet Majorana dark matter, for which a diagonal Z coupling generates the required SD interaction. The accompanying Higgs-mediated SI interaction would generically produce too many low-energy recoils, but can be suppressed along a Higgs blind spot while retaining a nonzero Z coupling. We find a region of the Higgs blind spot that simultaneously predicts an 𝒪(1) event rate in the LZ high-recoil window and reproduces the observed thermal relic abundance. The same SD interaction leads to solar capture, allowing this region to be tested independently with solar-neutrino searches. Current IceCube limits already probe part of the LZ-compatible thermal parameter space, while a viable region remains. Additional xenon exposure and improved solar-neutrino searches can therefore provide complementary tests of this interpretation.
SN - 2331-8422
ER -