Dr. Sangmin Choi (Ph.D. ’21) was one of the few students at U-M recently chosen for an Honorable Mention in the Rackham Graduate School’s 2021 ProQuest Distinguished Dissertation Awards competition. This award is meant to recognize highly accomplished graduate students who have produced exceptional dissertations in their field of study.

Dr. Choi was nominated for this recognition of scholarly excellence from among the many students who completed doctoral degrees last year at the University of Michigan. He was among a select student group who represent the best scholarly work published in Rackham dissertations across a broad range of disciplines.

Dr. Choi’s thesis is titled, “Dressings and Asymptotic Symmetries in Quantum Field Theory” and his interest lies in long-range interactions in quantum field theories including quantum electrodynamics (QED) and perturbative quantum gravity. QED is the modern theory of electrodynamics that incorporates both quantum mechanics and special relativity to describe interactions between charged particles like electrons. In quantum field theories, interactions are facilitated by gauge particles; for example, in QED, the interaction between two electrons occurs via a photon. In perturbative quantum gravity the interactions are mediated by massless gravitons. Dr. Choi’s work considers clouds of low-energy gauge particles, including photons and gravitons, introduced by long-range interactions. These particle clouds can be used to study quantum states on the event horizon of black holes, or the “boundary” of the black hole beyond which light and objects cannot escape. In his thesis, Dr. Choi studied these clouds in the theories of QED and perturbative quantum gravity with a goal of understanding the types of structure supported on the horizon of a black hole.

Dr. Choi received his Ph.D. in Physics in 2021 from the University of Michigan. He is currently a postdoctoral researcher at École Polytechnique in Paris.

Physics Professor Ratindranath Akhoury was Dr. Choi’s thesis advisor and comments on the accomplishment, “Sangmin’s thesis has made fundamental contributions to our understanding of gauge and gravitational theories by developing the concept of dressed states which are the building blocks for implementing asymptotic symmetries in these theories. This has a wide range of applications from defining finite scattering amplitudes to understanding possible structure on the black hole horizon.”

The awards will be presented at a virtual celebration in early April.

Dr. Sangmin Choi
Professor Ratindranath Akhoury