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Researchers from two major neutrino experiments have combined their data for the first time, producing some of the most precise measurements yet of how neutrinos change as they travel. The joint analysis, published in Nature, brings together results from the T2K experiment in Japan and the NOvA experiment in the United States. Scientists say the findings could help answer one of the biggest questions in physics: why the universe contains more matter than antimatter.
The study was co-led by Michigan State University physics and astronomy professor Kendall Mahn, who also serves as co-spokesperson for the T2K collaboration. The work was supported by the U.S. Department of Energy.
The research builds on a major discovery made over the past few decades that neutrinos have mass and can change from one type, or "flavor," to another as they travel. This process, called neutrino oscillation, is now one of the main ways scientists study these tiny particles and search for answers about how the universe evolved.
One of the biggest unanswered questions is why matter exists at all. Scientists believe the Big Bang should have produced equal amounts of matter and antimatter. If that had happened, the two would have destroyed each other, leaving behind only energy. Instead, matter survived, allowing galaxies, stars, planets and life to form. Physicists think neutrinos may help explain this imbalance if they behave differently from their antimatter counterparts, a phenomenon known as charge-parity (CP) symmetry violation.
