A collaborative study involving two significant neutrino experiments from Japan and the United States has provided new insights into the elusive particles known as neutrinos. These ghostly particles, which are formed in the cores of stars and during supernova explosions, are fundamental to our understanding of cosmic events and the origins of matter.
Neutrinos are the most abundant particles in the universe, passing through matter with ease and interacting very rarely. According to the new research, published in the journal Nature, the findings could help explain profound cosmic mysteries, including the dominance of matter over antimatter, the nature of dark matter and dark energy, and the mechanisms behind supernovae.
The NOvA experiment operates by directing a beam of neutrinos from the Fermi National Accelerator Laboratory in Illinois to a detector in Minnesota, covering a distance of 500 miles (810 km). In contrast, the T2K experiment sends a neutrino beam 185 miles (295 km) from Tokai in Japan to Kamioka. Although both projects investigate neutrino oscillations, they utilize different energies and detector designs, enriching the overall understanding of these particles.
Combining nearly a decade”s worth of data from both experiments, researchers have made significant advancements in measuring the differences in mass between the various types of neutrinos. “At first, there were questions regarding the compatibility of T2K and NOvA results, but we found they are indeed very compatible,” stated physicist Kendall Mahn from Michigan State University.
Scientists are still uncertain about the exact masses of the three neutrino types and which one is the lightest, a challenge known as “neutrino mass ordering.” Zoya Vallari, a physicist from Ohio State University, remarked, “This study measured the tiny mass difference between two of the three neutrinos with an unprecedented accuracy of less than 2% uncertainty.”
Besides measuring mass differences, the two experiments are also investigating whether neutrinos and their antiparticles oscillate in the same manner. Understanding this is critical in addressing why the universe is predominantly composed of matter rather than antimatter. During the Big Bang, it was expected that matter and antimatter would have existed in equal quantities and annihilated each other. “Yet, matter prevailed, and we exist because of it,” Vallari explained.
Addressing such fundamental questions demands extreme precision and statistical reliability, and researchers are looking forward to the next generation of large neutrino experiments. Upcoming projects, including the DUNE experiment led by Fermilab in Illinois and South Dakota, and the Hyper-Kamiokande project in Japan”s Gifu Prefecture, are already under development. Other initiatives, such as China”s JUNO project and space-based neutrino observatories like KM3NeT and IceCube, are also ongoing.
Mahn concluded, “Neutrinos possess unique properties, and our understanding of them continues to evolve.” This research marks a significant step forward in unraveling some of the universe”s most profound mysteries.
