Title and Abstract
Jin Chen
On Topological Defect Lines in Para-fermionic CFTs
In recent years, our understanding of categorical symmetries has been greatly evolved in terms of topological defect surfaces in QFTs of various dimensions. In this talk, I will discuss the features of a class of topological defect lines (TDLs) which correspond to non-invertible 0-form or 1-form symmetries in 2d para-fermionic CFTs or 3d anyon theories respectively. The talk is three-folded. First, TDLs can be studied in a pure 2d CFT perspective via a bottom-up approach; On the other hand, we can lift the TDLs into 3d anyon theories and understand them from the viewpoint of para-fermionic condensation in a top-down way; In addition, I will also explain the mathematical structures behind the TDLs in para-fermion/anyon theories, in terms of a generalized fusion category, Zn para-fusion categories.
Wei Cui
SymTFTs and Duality Defects from 6d SCFTs on 4-manifolds
In this work we study particular TQFTs in three dimensions, known as Symmetry Topological Field Theories (or SymTFTs), to identify line defects of two-dimensional CFTs arising from the compactification of 6d (2,0) SCFTs on 4-manifolds M4. The mapping class group of M4 and the automorphism group of the SymTFT switch between different absolute 2d theories or global variants. Using the combined symmetries, we realize the topological defects in these global variants. Our main example is P1 × P1. For N M5-branes the corresponding 2d theory inherits ZN0-form symmetries from the SymTFT. We reproduce the orbifold groupoid for theories with ZN0-form symmetries and realize the duality defects at fixed points of the coupling constant under elements of the mapping class group. We also study other Hirzebruch surfaces, del Pezzo surfaces, as well as the connected sum of P1 × P1. We find a rich network of global variants connected via automorphisms and realize more interesting topological defects. Finally, we derive the SymTFT on more general 4-manifolds and provide two examples.