Sterile-neutrino search based on 259 days of KATRIN data
Neutrinos are the most abundant fundamental matter particles in the Universe and play a crucial part in particle physics and cosmology. Neutrino oscillation, discovered about 25 years ago, shows that the three known species mix with each other. Anomalous results from reactor and radioactive-source e...
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| Main Authors: | , , , , , , |
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| Format: | Article (Journal) |
| Language: | English |
| Published: |
4 December 2025
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| In: |
Nature
Year: 2025, Volume: 648, Issue: 8092, Pages: 70-75, [1-19] |
| ISSN: | 1476-4687 |
| DOI: | 10.1038/s41586-025-09739-9 |
| Online Access: | Verlag, kostenfrei, Volltext: https://doi.org/10.1038/s41586-025-09739-9 Verlag, kostenfrei, Volltext: https://www.nature.com/articles/s41586-025-09739-9 
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| Author Notes: | The KATRIN Collaboration* |
| Summary: | Neutrinos are the most abundant fundamental matter particles in the Universe and play a crucial part in particle physics and cosmology. Neutrino oscillation, discovered about 25 years ago, shows that the three known species mix with each other. Anomalous results from reactor and radioactive-source experiments1 suggest a possible fourth neutrino state, the sterile neutrino, which does not interact through the weak force. The Karlsruhe Tritium Neutrino (KATRIN) experiment2, primarily designed to measure the neutrino mass using tritium β-decay, also searches for sterile neutrinos suggested by these anomalies. A sterile-neutrino signal would appear as a distortion in the β-decay energy spectrum, characterized by a discontinuity in curvature (kink) related to the sterile-neutrino mass. This signature, which depends only on the shape of the spectrum rather than its absolute normalization, offers a robust, complementary approach to reactor experiments. Here we report the analysis of the energy spectrum of 36 million tritium β-decay electrons recorded in 259 measurement days within the last 40 eV below the endpoint. The results exclude a substantial part of the parameter space suggested by the gallium anomaly and challenge the Neutrino-4 claim. Together with other neutrino-disappearance experiments, KATRIN probes sterile-to-active mass splittings from a fraction of an eV2 to several hundred eV2, excluding light sterile neutrinos with mixing angles above a few per cent. |
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| Item Description: | Online veröffentlicht: 03. Dezember 2025 *The KATRIN Collaboration: H. Acharya, L. Fallböhmer, L. Laschinger, T. Lasserre, S. Mertens, J. Plößner, F. Spanier [und 128 weitere Personen] Gesehen am 16.03.2026 |
| Physical Description: | Online Resource |
| ISSN: | 1476-4687 |
| DOI: | 10.1038/s41586-025-09739-9 |