Scientific American reports:

Trillions of neutrinos whiz through our bodies every day, pulsing from the sun, outer space and deep beneath Earth. Yet these elusive subatomic particles have proven difficult to study. That could soon change, however. Buried 700 meters beneath the rolling hills of southern China, an enormous neutrino observatory called JUNO has released its first results after a mere 59 days of operation. And so far, they are very promising, physicists say.

“The physics result is already world-leading in the areas that it touches,” says particle physicist Juan Pedro Ochoa-Ricoux of the University of California, Irvine, who co-leads a team on JUNO.

“In particular, we measured two neutrino oscillation parameters, and that measurement is already for both parameters the best in the world,” he says. The results were published in two separate preprints on arXiv.org.

JUNO—short for Jiangmen Underground Neutrino Observatory—has been tasked with a tall order: determine the ordering of masses of the three types of neutrino. In other words, do they follow a “normal mass ordering,” where the first flavor of neutrino is the lightest and the third the heaviest, or an inverted one, in which the third neutrino mass state is the lightest?

The answer to this question holds myriad implications, from informing other experiments to uncovering new physics to explaining certain cosmological mysteries. That’s because despite being such lightweights, neutrinos are so incredibly numerous that they may play an outsized role in the distribution of matter in the universe. [Continue reading…]