Professor Takuya Morozumi

Research Introduction

The subject I am currently working is research into the violation of charge parity (CP) symmetry. CP symmetry is a key symmetry, and many believe that CP violation and the asymmetry of matter and antimatter in our Universe are related to each other. However, revealing the connection between the asymmetry observed on a macroscopic scale and CP violation in the microscopic world is a challenging problem. The precision of measurements of CP violations in laboratory experiments under well-controlled conditions can be improved by repeating the measurements many times. In contrast, for the CP asymmetry observed in the Universe, experiments cannot be repeated. The matter-antimatter asymmetry that is observed today was produced only one time at a certain period in the history of the Universe. Therefore, to test theoretical hypotheses, it would be necessary to return to and observe that time armed with our present knowledge based upon the laws of nature. However, since the observable Universe is limited in size and our observations lack precision, this is difficult to achieve. Considering the situation, I am currently using a working hypothesis to study how the density of the matter-antimatter asymmetry evolves with time. We are working on a simple scalar field theory which includes only a complex scalar field, and have obtained interesting results which may relate to the question of the origin of matter (See R. Hotta, T. Morozumi, and H. Takata, Phys. Rev. D90 (2014) 016008).