Fermionic Dark Matter Absorption and the High-Energy Event in LUX-ZEPLIN
- 1Department of Physics and Institute of Theoretical Physics , Nanjing Normal University , Nanjing , 210023 , China
Abstract
The LUX-ZEPLIN (LZ) experiment has reported a single candidate event in the high-energy nuclear recoil window 248±32.5 keVnr with an exposure of 2.84 ton·yr, while the low-energy spectrum remains consistent with background expectations. We demonstrate that this excess can be naturally explained by the neutral-current absorption of fermionic dark matter on xenon nuclei. For a dark matter mass mχ≃ 247 MeV, the coherent absorption process produces a monoenergetic nuclear recoil at ER ≃ 248 keVnr. At this momentum transfer, the absorption process enters the incoherent regime, where scattering off individual nucleons produces a broad recoil spectrum extending from ∼ 200 keV to 100.2 MeV. We show that a single effective field theory coupling can simultaneously produce one event in the 248±32.5 keVnr window while remaining consistent with the non-observation of events in neighboring energy regions. The required single-nucleon absorption cross section is σχNNC = 1.07×10−46 cm2, corresponding to an effective field theory scale Λ≃ 11.5 TeV. However, a recasting analysis of KamLAND data on the neutron-emission channel χ+12C → ν+ n + 11C* excludes this benchmark parameter space, establishing a significant tension between the LZ excess interpretation and existing constraints from large-volume scintillator detectors. We discuss the implications of this tension and prospects for resolving it with future dedicated high-energy analyses.
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BibTeX
@misc{lou2026fermionic,
title = {{Fermionic Dark Matter Absorption and the High-Energy Event in LUX-ZEPLIN}},
author = {Yuanchao Lou and hih-Ting Lu},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.01592},
eprint = {2609.01592},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.01592},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Fermionic Dark Matter Absorption and the High-Energy Event in LUX-ZEPLIN
AU - Yuanchao Lou
AU - hih-Ting Lu
PY - 2026
DA - 2026/09/01
PB - arXiv
DO - 10.48550/arxiv.2609.01592
UR - https://arxiv.org/abs/2609.01592
AB - The LUX-ZEPLIN (LZ) experiment has reported a single candidate event in the high-energy nuclear recoil window 248±32.5 keV_nr with an exposure of 2.84 ton·yr, while the low-energy spectrum remains consistent with background expectations. We demonstrate that this excess can be naturally explained by the neutral-current absorption of fermionic dark matter on xenon nuclei. For a dark matter mass m_χ≃ 247 MeV, the coherent absorption process produces a monoenergetic nuclear recoil at E_R ≃ 248 keV_nr. At this momentum transfer, the absorption process enters the incoherent regime, where scattering off individual nucleons produces a broad recoil spectrum extending from ∼ 200 keV to 100.2 MeV. We show that a single effective field theory coupling can simultaneously produce one event in the 248±32.5 keV_nr window while remaining consistent with the non-observation of events in neighboring energy regions. The required single-nucleon absorption cross section is σ_χN^NC = 1.07×10^−46 cm^2, corresponding to an effective field theory scale Λ≃ 11.5 TeV. However, a recasting analysis of KamLAND data on the neutron-emission channel χ+^12C → ν+ n + ^11C^* excludes this benchmark parameter space, establishing a significant tension between the LZ excess interpretation and existing constraints from large-volume scintillator detectors. We discuss the implications of this tension and prospects for resolving it with future dedicated high-energy analyses.
SN - 2331-8422
ER -