Junctions, Edge Modes, and $G_2$-Holonomy Orbifolds

Abstract

One of the general strategies for realizing a wide class of interacting QFTs is via junctions and intersections of higher-dimensional bulk theories. In the context of string/M-theory, this includes many $D>4$ superconformal field theories (SCFTs) coupled to an IR free bulk. Gauging the flavor symmetries of these theories and allowing position dependent gauge couplings provides a general strategy for realizing novel higher-dimensional junctions of theories coupled to localized edge modes. Here, we show that M-theory on singular, asymptotically conical $G_2$-holonomy orbifolds provides a general template for realizing strongly coupled 5D bulk theories with 4D $\mathcal{N}=1$ edge modes. This geometric approach also shows how bulk generalized symmetries are inherited in the boundary system.

56 pages + appendices + refs, 18 figures