A collaboration between two leading neutrino experiments, NOVA in the US and T2K in Japan, is painting the most precise picture yet of neutrino oscillations – and may come closer to explaining why the universe is full of matter and not destroyed by antimatter.
A new global study reveals surprising behavior in the universe's most elusive particles, hinting at answers to why the universe even exists.
Joint research focuses on uncovering the unusual properties of the ghost particle
In a recent study, scientists have created the clearest and most detailed view yet of how neutrino particles change their "flavor" as they move through space.
Neutrinos are one of the fundamental building blocks of the universe, but they are still among the most difficult particles to study. They pass effortlessly through matter, making them nearly impossible to detect. Although much is still unknown about them, scientists have identified three distinct types of neutrinos: electron, muonic, and tauonic.
Understanding these different identities could help scientists know more about the masses of neutrinos and answer important questions about the evolution of the universe, including why matter became dominant over antimatter in the early universe, said senior lecturer Zoya Valari.
"The reason neutrinos are really, really fun is that they change their flavors," she said. "Imagine you get chocolate ice cream, you walk down the street and suddenly it turns into vanilla, and every time the ice cream moves, it changes again."
The science behind neutrino oscillations
This process, called neutrino oscillation, occurs in both naturally occurring neutrinos and those that scientists create in the laboratory. To study this remarkable shape-shifting behavior, scientists from two projects, NovA in the US and T2K in Japan, collaborated. They directed beams of neutrino particles over hundreds of kilometers, and tracked how their “flavor” changed along the way.
The scientific goals of NovA and T2K are similar, but the approaches are different. NovA's experiment sends a beam of muon neutrinos from the Fermi accelerator near Chicago to a remote detector in Fire River, Minnesota. T2K launches its muon neutrino beam from the east coast of Japan and measures it at a detector located in the mountains of western Japan.
“Our goals are similar, but the differences in experimental design add more information when we combine our data, because the sum is greater than its parts,” Valari said.
Looking for clues beyond the standard model
This study builds on previous work that found tiny, but still very significant, differences in the mass of each type of neutrino, but the researchers were looking for deeper clues that neutrinos operate outside the standard laws of physics. One of those questions is whether neutrinos and their antimatter counterparts behave differently, a phenomenon called charge-pair (CP) violation. If future data confirm this, researchers will be closer to figuring out how the universe came to be mostly matter, rather than being destroyed by antimatter after the Big Bang.
These findings do not provide a definitive answer about the role of neutrinos in the fabric of the universe, but they add to scientific knowledge about them.
"Our results show that more data is needed to give a meaningful answer to these fundamental questions," says Valari. "Hence the importance of building the next generation of experiments."
According to the study, combining the results of the two experiments allowed researchers to gain a deeper understanding of these pressing physics questions from different angles, because two experiments with different baselines and energies have a better chance of answering them than one experiment alone.
One response
The title is wrong. Even if there were equal amounts of matter and antimatter, the universe would exist and be full.
There was a lot (almost nothing) of radiation in it, and clouds of matter, and clouds of antimatter that didn't have time to annihilate each other and turn into radiation.