Physicists have long puzzled over the existence of “sterile” neutrinos, particles thought to account for some of the universe’s greatest mysteries. Two new experiments have failed to confirm these elusive particles, casting doubt on their potential role in explaining dark matter and other cosmic phenomena.
In a pair of papers published this week in Nature, researchers from the MicroBooNE experiment at Fermilab and the Karlsruhe Tritium Neutrino Experiment (KATRIN) presented findings that reject the sterile neutrino hypothesis. The experiments aimed to detect and count these ghostly particles, which are thought to interact with normal matter only through gravity.
The results of the new experiments do not rule out the possibility of sterile neutrinos entirely but suggest they may be less likely than previously thought. Dr. Thierry Lasserre, a physicist at the Max Planck Institute for Nuclear Physics in Germany, coordinated the analysis of data from KATRIN and said that all the findings are rejecting the sterile neutrino hypothesis.
While the results do not provide clear answers to the mysteries surrounding neutrinos, they have sparked renewed interest in alternative explanations. Dr. William Louis, a physicist at Los Alamos National Laboratory, noted that “neutrinos are a hotbed of inquiry” and that their behavior is more complicated than initially thought.
The failure to confirm sterile neutrinos highlights the ongoing challenges in understanding these enigmatic particles. Neutrinos are abundant but difficult to detect, and their interactions with normal matter remain poorly understood. The search for answers continues, with new experiments on the horizon.
Source: https://www.nytimes.com/2025/12/03/science/sterile-neutrinos-particle-physics.html