Speaker: Salvatore Pace (MIT)
Title: Emergent generalized symmetries in ordered phases and their spontaneous breaking.
Abstract: Based on recent work (arXiv:2308.05730) and upcoming work with Chenchang Zhu, Agnès Beaudry, and Xiao-Gang Wen, we will discuss (non-)invertible higher-form symmetries that emerge in generic ordered phases and their physical consequences. Such phases arise from spontaneously breaking an ordinary symmetry G down to a subgroup H, are described in the deep IR by a nonlinear sigma model with target space G/H, and are ubiquitous to condensed matter and high energy physics. We will focus on two aspects of this story: (1) when the generalized symmetry is finite, the fusion higher category describing its symmetry defects, and (2) its spontaneous breaking, which drives a phase transition to a nontrivial disordered phase with (non-)abelian topological orders and emergent photons. We will present examples for different groups G and H and construct lattice and continuum models that realize the generalized symmetry's spontaneous symmetry-breaking phases.