I work in theoretical elementary particle physics, high-energy astrophysics, and cosmology, trying to understand the nature of dark matter, the origin of ordinary matter, and the physics of the early universe. In addition, I am interested in physics beyond the standard model and neutrino physics. Furthermore, I have contributed to understanding of cosmic rays and gamma-ray signals from blazars, and the inferences regarding magnetic fields in the universe. In addition to a decade-long affiliation with IPMU, I hold an appointment of Professor of Physics and Astronomy at UCLA. I am a Fellow of American Physical Society and a member of Aspen Center for Physics.