My main interest lies in understanding why our universe looks the way it does today. Particle cosmology plays an important role in shedding light on the evolution of the universe as well as on the underlying fundamental theory.

In the early universe, interesting phenomena ─ completely different from those we see in everyday life ─ may have occurred. For instance, recent observations strongly suggest that there was an inflationary epoch during which the universe expanded at terrific speed. On the other hand, it is not fully known how the universe was heated or how the matter that constitutes our bodies was created after inflation.

Recently I have shown that an inflaton, the potential energy of which drives inflation, generically decays into standard-model particles as well as a superpartner of the graviton. I hope that this discovery will become an important guide to unravel the thermal history of the universe as well as the new physics beyond the standard model.