Always elusive, Fermi's "little neutral one" turns out to be a quick-change artist as well, offering answers and new questions for physics and cosmology
Last June the high-energy physics community celebrated a long-awaited result. The Japan-based Super-Kamiokande collaboration announced that it had detected oscillation in the elusive subatomic particles called neutrinos. Neutrinos come in three "flavors," and it now appears that they oscillate between these flavors as they propagate. The fact that they do so means that they have mass—a discovery that explains some of the missing mass in the universe, a major puzzle in cosmology. The authors describe the huge, water-filled underground detector that finally allowed physicists to detect and characterize the rare interactions that neutrinos have with other particles.
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