Heavy Higgsino Interpretation of the LZ Event
- 1Center for Theoretical Physics -a Leinweber Institute ,
- 2Massachusetts Institute of Technology , Cambridge , MA 02139 , USA
Abstract
The LZ experiment has recently reported a $248$ keV nuclear recoil event in a region where backgrounds are expected to be low. A pure higgsino scattering inelastically through a Z-boson is an exciting possible interpretation of this event, but at the mass required for thermal freeze-out to account for all dark matter, mχ= 1.1 TeV, it predicts several events in the empty high-energy sideband corresponding to ER≳350 keV and is further excluded by searches for high energy neutrinos coming from the Sun by the IceCube detector. We fit the higgsino mass scale and neutral state mass splitting, mχ and δ, to the event and the empty sideband. We additionally recompute solar capture bounds as a function of mχ. The LZ data alone are best fit at low mass, mχ≈ (240, 450) GeV, but is excluded by solar capture. The parameter space most consistent with the event, the empty sideband and the solar capture bound is $m_χ\approx (10^5,\,10^6) $ GeV with δ≈ (330, 480) keV, with some dependence on DM halo modeling. Such a higgsino must be produced by some other method than standard freeze-out; this can be achieved by freezing-out during a period of early matter domination which ends by reheating the universe to temperature TRH≈ 1 TeV. We give a simple proof of concept model which does this via a Kim-Nilles mechanism and therefore connects to the origin of the Higgsino mass scale and solves the strong CP problem.
Related
- Higgsino Dark Matter Interpretation of the LUX-ZEPLIN 248 keV Nuclear-Recoil Event
- Confronting the Higgsino Interpretation of the LZ Event with Astrophysical Uncertainties and the Solar Capture Constraints
- TeV Higgsino Interpretation of the LZ High-Recoil Event with Intermediate-Scale Electroweak Gauginos
- Confronting the Higgsino Interpretation of the LZ Event with the High-Energy Sideband
- Heavy Higgsino Dark Matter With Low Reheating in View of the LZ High-Recoil Event
BibTeX
@misc{langhoff2026heavy,
title = {{Heavy Higgsino Interpretation of the LZ Event}},
author = {Kevin Langhoff},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.09385},
eprint = {2609.09385},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.09385},
note = {CC0},
}
RIS
TY - UNPB
TI - Heavy Higgsino Interpretation of the LZ Event
AU - Kevin Langhoff
PY - 2026
DA - 2026/09/08
PB - arXiv
DO - 10.48550/arxiv.2609.09385
UR - https://arxiv.org/abs/2609.09385
AB - The LZ experiment has recently reported a $248$ keV nuclear recoil event in a region where backgrounds are expected to be low. A pure higgsino scattering inelastically through a Z-boson is an exciting possible interpretation of this event, but at the mass required for thermal freeze-out to account for all dark matter, m_χ= 1.1 TeV, it predicts several events in the empty high-energy sideband corresponding to E_R≳350 keV and is further excluded by searches for high energy neutrinos coming from the Sun by the IceCube detector. We fit the higgsino mass scale and neutral state mass splitting, m_χ and δ, to the event and the empty sideband. We additionally recompute solar capture bounds as a function of m_χ. The LZ data alone are best fit at low mass, m_χ≈ (240, 450) GeV, but is excluded by solar capture. The parameter space most consistent with the event, the empty sideband and the solar capture bound is $m_χ\approx (10^5,\,10^6) $ GeV with δ≈ (330, 480) keV, with some dependence on DM halo modeling. Such a higgsino must be produced by some other method than standard freeze-out; this can be achieved by freezing-out during a period of early matter domination which ends by reheating the universe to temperature T_RH≈ 1 TeV. We give a simple proof of concept model which does this via a Kim-Nilles mechanism and therefore connects to the origin of the Higgsino mass scale and solves the strong CP problem.
SN - 2331-8422
ER -