Research
As a theoretical physicist, I pursue research at the interface of particle physics, nuclear physics, and cosmology. I lead a global team that addresses key open questions at this interface:
- Why does the Universe contain more matter than antimatter?
- What is the thermal history of electroweak symmetry-breaking?
- What is the origin of the tiny but non-zero neutrino masses?
- What are the new laws of nature that answer these and other puzzles not addressed by the Standard Model and General Relativity?
- How do we apply the ideas and methods of quantum field theory to answer these questions?
As described in the Current Research page, we explore answers to these questions in three broad areas: quantum field theory of the early universe; tests of fundamental symmetries and studies of neutrino properties; and precision calculations.
To date, my research has contributed to our understanding of physical phenomena at a variety of energy scales, including
- The thermal history of electroweak symmetry-breaking and implications for the origin of the cosmic matter-antimatter asymmetry
- Probes of extended Higgs sectors at the Large Hadron Collider and prospective future high-energy colliders
- Tests of fundamental interactions using nucleons and nuclei
- Internal structure of nucleons as viewed by low-energy probes
The American Physical Society recognized my contributions to the arena of fundamental symmetries and neutrinos with the 2023 Herman Feshbach Prize in Theoretical Nuclear Physics. Previously, I became an APS Fellow in 2000 and received the 1990 Dissertation Award in Nuclear Physics from the APS Division of Nuclear Physics.
I also provide global scientific leadership as a member of the Particle Data Group, the editorial board of the journal Physics Reports, and several international scientific advisory committees.
I invite you to learn more about our exciting current research, primary accomplishments, publications, and recent scientific presentations. I am particularly proud of our unique, world-leading program investigating the possibility of an electroweak phase transition in the early universe. I invite early career physicists to consider joining our diverse, global team of ~ 20 talented post-docs and students in Shanghai and Amherst and to hear from current and former team members about their experience.
Was there an electroweak phase transition?
We know from lattice studies that the electroweak symmetry breaking transition in a purely Standard Model universe is a smooth crossover transition. The presence of beyond Standard Model physics, particularly extended Higgs sectors, can dramatically alter this thermal history, leading to the occurrence of a first order electroweak phase transition. This possibility is both intrinsically fascinating and consequential. If a first order electroweak phase transition took place, it would provide needed preconditions for generating the cosmic matter-antimatter asymmetry and lead to generation of potentially detectable gravitational waves.