Mr. Mahesh K N Balasubramanian | Gauging non-invertible symmetries in 2+1d TQFTs

Mr. Mahesh K N Balasubramanian | Gauging non-invertible symmetries in 2+1d TQFTs

🎙 Mahesh K N Balasubramanian 👥 2K 📅 November 10, 2025 ⏱ 83 min 👁 172 📄 original study 🧭 2026-08-15
Available in: English (current) Français

Keywords

non-invertible symmetryTQFTmodular tensor categorygauginganyon condensation

Summary

The talk, given by Mahesh K N Balasubramanian at the Isaac Newton Institute, presents a framework for gauging non-invertible symmetries in 2+1d topological quantum field theories (TQFTs). The speaker begins by reviewing modular tensor categories (MTCs) as the mathematical structure capturing one-form symmetries in 3D TQFTs, using the example of U(1) Chern-Simons theory. He then outlines the known procedure for gauging invertible symmetries, which involves extending the MTC by twisted sectors and then performing equivariantization. The main goal is to generalize this to non-invertible symmetries, which are implemented by surface operators. Using the toric code as a concrete example, he illustrates how a non-invertible symmetry (the S_E surface) acts on line operators and how twisted sectors are introduced. The talk emphasizes a simplified approach: given the gauged theory, one can understand the properties of the added defects via anyon condensation and fixed-point theorems. The speaker concludes by discussing open questions, such as the uniqueness of the symmetry action on twisted sectors.

161 words

Critical Evaluation

Value of the Information & Strength of the Argument

The talk provides a valuable overview of a cutting-edge topic in mathematical physics, presenting original research that extends known results to non-invertible symmetries. The argumentation is logical and builds on established concepts, but the presentation is dense and assumes a high level of expertise. The speaker effectively uses the toric code as a concrete example to illustrate abstract ideas, which aids comprehension. However, some steps are hand-waved, and the audience interaction suggests that certain points require further clarification. The value lies in the conceptual framework and the proposed methodology, which could guide future research.

Scientific Rigor, Source Quality, Title Accuracy

The talk demonstrates scientific rigor by grounding the discussion in established mathematical structures (MTCs, fusion categories) and citing relevant literature (e.g., Etingof-Nikshych-Ostrik, and recent works on non-invertible symmetries). The sources mentioned are appropriate and current. The title accurately reflects the content, and the presentation is consistent with the advertised topic. The speaker acknowledges limitations and open questions, which adds to the credibility. The lack of detailed references in the description is a minor drawback, but the talk itself is well-referenced.

189 words

Title / Content Match

The title accurately reflects the content: the speaker discusses gauging non-invertible symmetries in 2+1d TQFTs, with a focus on extending known results for invertible symmetries.

Quality & Reliability

8/10

The talk is a research seminar by an expert, presenting original work with mathematical rigor. The content is technical and consistent with current literature, but the presentation is informal and lacks detailed derivations, making verification difficult for non-specialists.

Key Moments

Cited Sources

Concurring Sources

Contribution & Novelties

The talk presents a novel approach to gauging non-invertible symmetries in 2+1d TQFTs, building on the speaker’s recent paper. The key contribution is a simplified methodology that leverages anyon condensation and fixed-point theorems to determine the properties of twisted sectors without solving complex polynomial equations. This offers a practical shortcut for understanding the gauged theory. The talk also clarifies the role of self-junctions in determining the number of twisted sectors for non-invertible symmetries.

Pour aller plus loin :

111 words

Radar Profile

The radar profile shows high scores in technical level and information quality, reflecting the advanced and rigorous nature of the talk. The lower score in 'quantite_information' suggests that while the content is dense, the presentation may not cover all aspects in depth due to time constraints. Overall, the talk is highly specialized and valuable for experts.

Reliability 8/10