Ross Dempsey, Pappalardo Fellow

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Area of Physics

High Energy and Particle Theory

Research Interests

Quantum chromodynamics (QCD) was established as the gauge theory governing the strong nuclear force over 50 years ago. Despite this long history, it remains very difficult to make predictions about the strong nuclear force by starting from QCD, because many of our best-understood methods for studying quantum field theories are only applicable to weakly-coupled interactions. Even the most apparent feature of QCD, the robust confinement of quarks and gluons into color-neutral hadrons, remains stubbornly impervious to analytic approaches.

Driven by this central puzzle in theoretical particle physics, Ross Dempsey’s research focuses on tools for making predictions about the observable data of strongly-coupled gauge theories. During his Ph.D., he worked on augmenting conformal bootstrap methods with input from supersymmetric localization; this provided a new window into N = 4 super-Yang-Mills theory, a frequently-studied cousin of QCD. He also worked extensively on Hamiltonian lattice gauge theory, developing a significant improvement to a decades-old method for simulating two-dimensional quantum electrodynamics and extending this method to two-dimensional QCD.

Ross is now working to leverage these non-perturbative techniques for various important physical questions about strongly-coupled gauge theories. In particular, he is interested in simulating real-time processes, such as particle collisions.

Biographical Sketch

Ross Dempsey grew up in Virginia near Washington, DC, and was an undergraduate at Johns Hopkins. He was introduced to the joys of astrophysics research by Prof. Nadia Zakamska, with whom he worked on quasar winds and a spectacular system in the Orion Nebula. He was slowly but steadily coaxed into pursuing high-energy theory by Prof. Ibou Bah, with whom he studied hidden structure in the Einstein equations.

He moved to Princeton for his Ph.D., where he was advised by Prof. Silviu Pufu. There he worked on a variety of analytic and computational tools for probing the non-perturbative dynamics of strongly-coupled gauge theories. In particular, he collaborated extensively with Prof. Igor Klebanov as well in research on two-dimensional gauge theories.

Ross is passionate about physics education and outreach, and is always looking for ways to engage with students of all levels. He especially enjoys working with the Department of Energy’s National Science Bowl competition for middle- and high-school students.

Selected Publications

• Ross Dempsey, Igor R. Klebanov, Silviu S. Pufu, and Bernardo Zan. “Discrete chiral symmetry and mass shift in the lattice Hamiltonian approach to the Schwinger model”. In: Phys. Rev. Res. 4 (4 Nov. 2022), p. 043133. arXiv: 2206.05308
• Ross Dempsey, Igor R. Klebanov, Silviu S. Pufu, Benjamin T. Søgaard, and Bernardo Zan. “Phase Diagram of the Two-Flavor Schwinger Model at Zero Temperature”. In: Phys. Rev. Lett. 132.3 (2024), p. 031603. arXiv: 2305.04437
• Shai M. Chester, Ross Dempsey, and Silviu S. Pufu. “Bootstrapping N = 4 super-Yang-Mills on the conformal manifold”. In: JHEP 01 (2023), p. 038. arXiv: 2111.07989
• Ross Dempsey, Silviu S. Pufu, Benjamin T. Søgaard, and Igor R. Klebanov. “More About the Lattice Hamiltonian for Adjoint QCD2”. arXiv: 2409.19164
• Ross Dempsey, Igor R. Klebanov, and Silviu S. Pufu. “Exact symmetries and threshold states in two-dimensional models for QCD”. in: JHEP 10 (2021), p. 096. arXiv: 2101.05432