Speaker: Ken Kikuchi (YMSC, Tsinghua)
Title: Emergent symmetry and free energy
Abstract: Most of the problems in physics can be summarized as follows; what happens to ultraviolet symmetry in infrared? One possible answer is the spontaneous symmetry breaking (SSB). It is well-known that SSB can be understood via free energy. Another possible answer is an emergence of symmetry. We explain emergent symmetries can also be understood via free energy. More concretely, focusing on rational conformal field theories, we answer three questions; i) when symmetries emerge, ii) why they appear, and iii) what are the structures (including ‘size’) of emergent symmetries. To achieve the goal, we introduce new constraints on renormalization group (RG) flows. As a byproduct, we find discrete quantities can jump under RG flows (‘counterexamples’ to the Ocneanu rigidity argument).
Date & Time: 2:00 PM, Sep 7, 2022.