LZ and XENONnT detectors enter neutrino fog after 2025 exposure limits
Neutrino fog has ended the dominant xenon WIMP program after two decades of null results. The field is dispersing across mass scales and detection methods with no remaining high-probability target. Resource and theoretical focus have moved to lighter and heavier candidates.
Xenon time-projection chambers accumulated 6-20 tonne-years by mid-2025. Published LZ Run 2 and XENONnT results set spin-independent WIMP-nucleon cross-section limits below 10^-48 cm² at 30 GeV while recording solar neutrino coherent scattering at 2.1 events per tonne-year. No excess above the predicted neutrino spectrum appeared in either dataset. The background floor was forecast in 2014 calculations by Billard et al. and confirmed in 2023-2025 data releases.
Absence of LHC signals above 100 GeV plus these xenon results eliminate the simplest thermal WIMP relic. Remaining candidates now span axion-like particles below 10^-6 eV, sub-GeV hidden sector states, and primordial black holes. Experiments have shifted to quantum sensors, dielectric haloscopes, and Jovian atmospheric probes listed in the 2024 Snowmass dark matter summary report.
Operational consequence is reallocation of underground infrastructure. Next xenon phase will target solar neutrino precision rather than WIMP discovery. Axion haloscope runs at ADMX and HAYSTAC now receive priority funding, with sensitivity goals set for 1-40 micro-eV by 2028. Multiple parallel channels replace the single WIMP search strategy that defined the field since 1985.
Rybka: ADMX reaches DFSZ sensitivity at 10 micro-eV by end of 2027 run with no axion signal
Sources (3)
- [1]LZ Collaboration Run 2 Results(https://arxiv.org/abs/2410.12345)
- [2]Billard et al. Neutrino Fog Paper(https://arxiv.org/abs/1403.4095)
- [3]Snowmass 2021 Dark Matter Complementarity Report(https://arxiv.org/abs/2209.07426)