Why in our world has matter taken over antimatter, its inverted double, when at the origin of the Universe they were produced in equal quantities and should have been annihilated? Science has yet to unravel this mystery. An international team believes, however, to have taken a step to explain this asymmetry. She found a difference in behavior between neutrinos and antineutrinos.
The research, co-directed by Professor Federico Sanchez Nieto, of theUniversity of Geneva (UNIGE), were conducted in Japan using the Super Kamiokande, a detector built under a mountain. Before obtaining significant results, the scientists of the T2K collaboration had to be patient, however.
An international scientific team, co-led by @UNIGEnews, succeeded in detecting a manifestation of the break in the fundamental symmetry of nature which allowed the # material to dominate#Universe at the expense of#antimatter. https://t.co/0MjCSGrnPz pic.twitter.com/It9Kps2u5j
– University of Geneva (@UNIGEnews) April 15, 2020
Neutrinos and antineutrinos
It took them ten years of effort to collect enough data. The neutrino, like its opposite twin the antineutrino, is indeed a particle almost impossible to trace. Huge amounts of neutrinos pass through the Earth every second. However, they are only a handful to interact with its atoms.
The consortium of researchers relied on the characteristics of the neutrino in its work. The particle exists in three “flavors” and can sometimes switch from one to the other spontaneously. This is called an oscillation, explains in a UNIGE press release published on Wednesday by Professor Sanchez Nieto.
“What we have done is to see if the neutrinos oscillate at the same rate as the antineutrinos, in this case from the muon flavor to the electron flavor,” emphasizes the Geneva physicist. The data that has been collected over the years thanks to Super Kamiokande allows us to conclude that this is not the case.
Significant imbalance
The researchers observed a total of 90 electron neutrinos and 15 electron antineutrinos meeting their criteria. According to UNIGE, this result, after careful analysis, turns out to be compatible with a maximum break in charge-parity (CP) symmetry in favor of neutrinos and against antineutrinos.
“Our results show a strong preference for the material,” notes Sanchez Nieto. The professor stresses, however, that it is still premature to state formally that the CP symmetry has been violated. Researchers will have to continue their work by improving the sensitivity of their experience and accumulating more data.
In 1964, physicists had already tried to explain the abundance of matter compared to antimatter by studying the behavior of quarks and antiquarks. A difference had been observed at the time. “But it was too weak to explain the imbalance,” notes UNIGE.
The T2K experiment was built and is conducted by an international collaboration currently comprising 500 researchers from 12 countries. The National Fund for Scientific Research supports this project, in particular through the universities of Geneva and Bern and the Federal Polytechnic School of Zurich.
The results of the work carried out by T2K were published in the journal “Nature”. (ats / nxp)
Created: 04.15.2020, 5:15 p.m.
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