Résumé |
Quantum field theories (QFTs) in various dimensions can exhibit rich and complex behavior when extended objects?defects?are introduced. These defects lead to interesting dynamical phenomena that are often challenging to study directly. One of the key questions in defect quantum field theories (DQFTs) is understanding how these defects behave under renormalization group (RG) flow, as this can be complicated and difficult to analyze in many setups. In this talk, I will explore how the interplay between bulk symmetries and defects imposes non-trivial constraints on the fixed points of the RG flow. I will introduce the concept of strongly symmetric defects, which, under certain conditions, cannot decouple from the bulk theory during RG flow. Furthermore, I will define the notion of defect anomaly, akin to the ?t Hooft anomalies in conventional QFTs, which provides additional constraints on the possible IR limits of DQFTs. These ideas will be illustrated with concrete examples in 1+1 and 2+1 dimensions. Specifically I will consider the RG flow of strongly symmetric lines in 1+1 dimensional CFTs and strongly symmetric surface defects in 2+1 dimensional scalar QED. Based on 2412.18652. |