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Abstract:
Invertible and symmetry-protected topological phases can be organized using bordism groups and their duals. In this talk I will discuss bosonic phases described by oriented bordism, focusing on the first beyond-cohomology phenomena in the Atiyah-Hirzebruch spectral sequence. Unlike the fermionic Gu-Wen supercohomology story, where the first correction is mod 2, the corresponding bosonic effect is mod 3 and is tied to the first Pontryagin class.
I will explain several low-dimensional examples, including finite symmetry groups and higher-form symmetry backgrounds, and show how spectral-sequence extension problems determine the group of phases. I will also describe a 6+1 dimensional Dijkgraaf-Witten phase which is nontrivial on general spaces but vanishes on manifolds, giving a physical counterpart of the classical Steenrod problem.
Biography:
He received his Bachelor of Science degree from Heidelberg University, Germany, in 2015, followed by a Master’s degree in Physics and the Diplôme de l’École Normale Supérieure from École Normale Supérieure, Paris, in 2017. In 2021, he earned his Ph.D. in Physics from the Institute of Theoretical Physics (IPhT/CEA Saclay), Paris-Saclay University. In 2020 and 2021, he was invited as a long-term visitor to the Max Planck Institute for Gravitational Physics, also known as the Albert Einstein Institute, in Potsdam, Germany, and to the Korea Institute for Advanced Study (KIAS) in Seoul, South Korea. From 2022 to 2024, he conducted postdoctoral research at Peking University. Since 2024, he has been a postdoctoral researcher at Kavli IPMU, University of Tokyo. His research focuses on the algebraic, geometric, and topological structures underlying string theory, quantum field theory, and supergravity, with particular emphasis on symmetries and anomalies.
Alternative online link: https://meeting.tencent.com/dm/HFMdcR9w7Uxu
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