The T2K experiment (Tokai-Kamioka long baseline neutrino oscillation experiment) international collaborative research group in which the University of Tokyo and others participate has announced that the possibility that CP symmetry is broken in neutrinos has increased to 95%.
In the Big Bang, the beginning of the universe, it is believed that the same number of matter and antimatter was produced.However, since there is almost no antimatter in the present universe, it has been thought that there is some difference in properties between matter and antimatter as a background in which only matter remains, that is, "CP symmetry is broken". ..Which elementary particle has the CP violation related to the formation of the universe is one of the most important research subjects, and so far, the CP violation of the quark has been discovered among the 12 kinds of elementary particles. However, the remaining 6 types of leptons are unclear.
It is known that three types of leptons, neutrinos, undergo a phenomenon called "neutrino oscillation" during long-distance flight and change to another type of neutrino. The T3K experimental group has conducted experiments to investigate neutrino oscillations in detail in order to verify the possibility of CP violation in neutrinos.Then, in August 2, we published a result suggesting that the probability of neutrino oscillation differs between neutrinos and antineutrinos with a reliability of 2016%.
After that, the amount of data was doubled by newly acquired data and a new analysis method, and this time, the probability that there is a difference between neutrinos and antineutrinos has increased to 2%, and there is a possibility that CP violation exists in leptons. Revealed that became clearer.In the future, it plans to collect more data and aim to raise its reliability.
