Field theories and critical excitations at anyon condensation transitions

Abstract

Anyon condensation transitions remain challenging to characterize especially when the condensing anyons are non-abelian. We develop two complementary approaches for extracting information about the transition from the categorical data of the parent topological order and the condensate. The first adapts a Ginzburg-Landau procedure developed for $1+1$D transitions in the SymTFT setting to $2+1$D anyon condensation transitions. The construction applies when the anyons participating in the condensate have integer quantum dimensions. The second gives a criterion for identifying which point and loop excitations become critical at a continuous transition. The key step is to determine which anyon loops remain condensed throughout. All other loops become critical, while a point excitation becomes critical if it braids trivially with every condensed loop. We illustrate both proposals in several abelian and non-abelian examples.