My research is in the field of particle cosmology, the interplay between particle physics and cosmology. I would like to understand how the Universe was born and evolved into the present state, namely, how inflation occurred, how the hot Big Bang Universe was created after inflation, how dark matter as well as matter-antimatter asymmetry were generated, how matter fluctuations grew to form stars, galaxies and clusters of galaxies through gravitational instabilities, why the current cosmic expansion is accelerated, etc. These issues cannot be fully answered without knowing particle physics at very high energies. In particular, dark matter is considered to be made of yet unknown particles, which requires physics beyond the standard model. One can also constrain various candidates for physics beyond the standard model by studying their cosmological implications.

I was interested in the Universe, stars, and planets since childhood. In high school,　I was fascinated by physics. When I was an undergraduate student, I wanted to be a theoretical physicist in particle physics. Just before applying for the graduate school entrance examination, I learned that there is a field called particle cosmology, and I thought “This is it!”. Also, by that time, it had become clear that our Universe is dominated by something unknown, and "particle cosmology" seemed very attractive to me.

By now, a sort of the standard paradigm for cosmology, known as the Lambda CDM model, has been established by the huge stock of observational and experimental data. For instance, the present abundances of baryon, dark matter and dark energy have been precisely measured, and we know that inflation can be well described by a scalar field slowly rolling on a very flat potential. On the other hand, there are a lot of things that we do not understand at all. For example, the identity of dark matter and dark energy remain a complete mystery, and various experiments and observations are ongoing or under planning to answer these questions. Students as well as post-docs who are interested in addressing these great mystery of nature are welcomed.