From pq-webs to magnetic quivers and back II: distributional indices and 5d theories breaking bad

Abstract

This is the second of two companion papers in which we study five-dimensional $\mathcal{N}=1$ theories engineered by $(p,q)$ five-brane webs and their associated three-dimensional magnetic quivers. Leveraging the exact parameter dictionary between the $N+\mathrm{SU}(N)_0^{k-1}+N$ theories and their magnetic quivers at infinite coupling, proposed in the first paper, we investigate nilpotent moment-map VEV deformations and their three-dimensional counterparts. We show that, when the Higgsing is excessive, the five-dimensional superconformal index becomes distributional, mirroring a characteristic feature of bad and broken theories in three dimensions. We also develop a five-brane web interpretation of these results, identifying the Hanany-Witten moves associated with the Higgsing cascade and relating inequivalent frames to distinct tessellations of the generalised toric diagram.