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High Energy Theory Seminar

Wednesday, January 28, 2026
11:00am to 12:00pm
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Online and In-Person Event
Particle-Soliton Degeneracy in 2D QCD from Spontaneously Broken Non-invertible Symmetry
Diego Garcia Sepulveda, Harvard University,

Quantum chromodynamics in two spacetime dimensions admits a finite non-invertible symmetry described mathematically by a fusion category. This symmetry is spontaneously broken at long distances, leading to distinct vacua. When the theory has a mass gap, the spectrum is therefore characterized by particle excitations above a single vacuum and soliton sectors interpolating between vacua. In this talk, I will explain how to use the theory of 2D topological cosets, anyon condensation of 3D TQFTs, and the representation theory of fusion categories to obtain exact results about this spectrum. Often, particles and solitons are in the same representation and therefore must have equal masses. Furthermore, the fusion category symmetry frequently implies the existence of certain stable states in the spectrum. The resulting degeneracies are encoded in quiver diagrams where nodes are vacua and arrows are excited states. I will also comment on some recent results corroborating the predictions associated with this non-invertible symmetry.

Contact [email protected] for Zoom information.