The T2K experiment (Tokai-Kamioka long baseline neutrino oscillation experiment) showed results suggesting "CP violation" in neutrinos.Researchers such as Mark Hartz, a specially appointed assistant professor of the Kavli Institute for the Physics and Mathematics of the Universe, the University of Tokyo, are participating in the joint research group.
According to the standard model in particle physics, antiparticles that make antimatter are also generated in the generation of particles that make up matter, and it is said that the same amount was generated in the early universe.However, in the present universe, only matter exists, and antimatter is rarely observed.The theory of CP violation (difference in the properties of matter and antimatter) in neutrinos (one of the elementary particles) explains the asymmetry between matter and antimatter.
The T2K experiment is the first experiment in the world that can search for CP symmetry in neutrinos by investigating the neutrino oscillations of neutrinos and antineutrinos.In the experiment, a high-intensity mu-type neutrino beam (or anti-mu-type neutrino beam) was generated at the high-intensity proton accelerator facility J-PARC (Tokai-mura, Ibaraki Prefecture), and a cosmic ray study in Kamioka, Hida City, Gifu Prefecture, 295 km away. It shoots at the Super-Kamiokande detector at the place and examines the difference in the probability that it will change to electronic neutrinos or anti-electronic neutrinos.
Data analysis of dozens of neutrinos detected so far and subsequent verification show differences in the probability of neutrino oscillations between neutrinos and antineutrinos, indicating the possibility of CP violation in neutrinos. Was done.Furthermore, we are currently acquiring a considerable amount of new data on electronic neutrinos, and it is expected that the results of this analysis will be shown by the end of the year.
Paper information:[Physical Review Letters] Combined Analysis of Neutrino and Antineutrino Oscillations at T2K
