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PreprintCC BY 4.0arXiv

Confronting the Higgsino Interpretation of the LZ Event with the High-Energy Sideband

  • Nicholas L. Rodd1,2
  • Benjamin R. Safdi1,2
  • Tracy R. Slatyer3,4
  • Weishuang Linda Xu5,6
6 affiliations
  1. 1Leinweber Institute for Theoretical Physics , University of California , Berkeley , CA 94720 , USA
  2. 2Theory Group , Lawrence Berkeley National Laboratory , Berkeley , CA 94720 , USA
  3. 3Center for Theoretical Physics -a Leinweber Institute ,
  4. 4Massachusetts Institute of Technology , Cambridge , MA 02139 , USA
  5. 5Kavli Institute for Particle Astrophysics & Cosmology , Stanford University , Stanford , CA 94305 , USA
  6. 6Particle Theory Group , SLAC National Accelerator Laboratory , Stanford , CA 94305 , USA
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Abstract

The LZ experiment has reported a single 248 keV nuclear recoil event in their $2.84$ ton-yr exposure on a xenon target. The absence of lower nuclear recoil events is naturally explained by inelastically scattering dark matter (DM), for which the nuclear recoil energy spectra are shifted upwards from zero. Excitingly, the observed rate and spectra are consistent with a thermal $1.1$ TeV higgsino that explains all of DM with a mass splitting δ∼ 370 − 490 keV between the two lowest-lying Majorana states, with the range depending on the underlying DM velocity distribution. In this work, however, we show that higgsino DM with these properties would generically produce more higher-energy recoil events in a high-energy sideband along the LZ S1c energy axis, while the LZ experiment reports no events in that bin. This suggests a possible tension which could be further explored by the LZ Collaboration, as the acceptance in that bin is not public. We further show that a non-thermal ∼500 GeV higgsino may evade the sideband constraint and that future experiments using heavy targets can potentially test the higgsino interpretation of the event either way.

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Cite

BibTeXRIS
BibTeX
@misc{rodd2026confronting,
  title = {{Confronting the Higgsino Interpretation of the LZ Event with the High-Energy Sideband}},
  author = {Nicholas L. Rodd and Benjamin R. Safdi and Tracy R. Slatyer and Weishuang Linda Xu},
  howpublished = {arXiv},
  year = {2026},
  month = sep,
  doi = {10.48550/arxiv.2609.04175},
  eprint = {2609.04175},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2609.04175},
  note = {CC BY 4.0},
}
RIS
TY  - UNPB
TI  - Confronting the Higgsino Interpretation of the LZ Event with the High-Energy Sideband
AU  - Nicholas L. Rodd
AU  - Benjamin R. Safdi
AU  - Tracy R. Slatyer
AU  - Weishuang Linda Xu
PY  - 2026
DA  - 2026/09/03
PB  - arXiv
DO  - 10.48550/arxiv.2609.04175
UR  - https://arxiv.org/abs/2609.04175
AB  - The LZ experiment has reported a single 248 keV nuclear recoil event in their $2.84$ ton-yr exposure on a xenon target. The absence of lower nuclear recoil events is naturally explained by inelastically scattering dark matter (DM), for which the nuclear recoil energy spectra are shifted upwards from zero. Excitingly, the observed rate and spectra are consistent with a thermal $1.1$ TeV higgsino that explains all of DM with a mass splitting δ∼ 370 − 490 keV between the two lowest-lying Majorana states, with the range depending on the underlying DM velocity distribution. In this work, however, we show that higgsino DM with these properties would generically produce more higher-energy recoil events in a high-energy sideband along the LZ S1c energy axis, while the LZ experiment reports no events in that bin. This suggests a possible tension which could be further explored by the LZ Collaboration, as the acceptance in that bin is not public. We further show that a non-thermal ∼500 GeV higgsino may evade the sideband constraint and that future experiments using heavy targets can potentially test the higgsino interpretation of the event either way.
SN  - 2331-8422
ER  -