Tensor stable moduli stacks and refined representations of quivers

Abstract

In this paper, we look at the problem of modular realisations of derived equivalences, and more generally, the problem of recovering a Deligne-Mumford stack $\mathbb{X}$ and a bundle $\mathcal{T}$ on it, via some moduli problem (on $\mathbb{X}$ or $A = \operatorname{End}_{\mathbb{X}} \mathcal{T}$). The key issue is, how does one incorporate some of the monoidal structure of $\operatorname{Coh}(\mathbb{X})$ into the moduli problem. To this end, we introduce a new moduli stack, the tensor stable moduli stack which generalises the notion of the Serre-stable moduli stack. We then show how it can be used both for stack recovery and the modular realisation problem for derived equivalences. We also study the moduli of refined representations and how it addresses these problems. Finally, we relate the two approaches when $\mathcal{T}$ is a tilting bundle which is a direct sum of line bundles.