Department of Physics, Graduate School of Science
My specialty is particle physics experiments, and I am participating in the KOTO experiment, which searches for rare decays of neutral K mesons.
In the early universe, equal amounts of matter and antimatter are produced, but in our current universe, there is almost exclusively matter. This asymmetry between matter and antimatter is called CP violation, and our universe must have a mechanism that breaks CP symmetry. Although the current theoretical framework of particle physics (The Standard Model) has succeeded in explaining most of the universe, it still falls short in some respects and does not fully explain the CP asymmetry.
The KOTO is looking for a new physics beyond the Standard Model by searching the rare kaon decay
. The branching ratio of this decay is very small 3 × 10－11 and the theoretical uncertainty is also small, so that even a small deviation from the theoretical value in the measured branching ratio is evidence for the existence of new physics.