Han’s research is in elementary particle physics theory, focusing on high-energy collider physics and in connection to astro-particle physics and cosmology. He formulates theoretical models of elementary particles and their interactions and develops strategies to test the theory by experiments and observations. This research, bridging the abstract theory and experimental observation, is the field of phenomenology.
The fundamental questions Han has been pursuing include the origin of mass for elementary particles, fundamental forces and their unification, symmetries and their breakdown, the nature of particle dark matter, and the property of space-time. In addition, he has worked for decades on the Higgs boson, a particle believed to be the fundamental building block of the universe.