Perverse sheaves with nilpotent singular support on the stack of coherent sheaves on an elliptic curve

TL;DR

This paper provides a detailed geometric and combinatorial analysis of perverse sheaves with nilpotent singular support on the moduli stack of coherent sheaves over an elliptic curve, linking geometric components with algebraic categorifications.

Contribution

It introduces a stratification of the moduli stack, explicitly describes irreducible components, and establishes a bijection with simple objects in a categorified algebraic setting.

Findings

Explicit description of irreducible components of the global nilpotent cone

Bijection between simple perverse sheaves and irreducible components

Parametrization of perverse sheaves with nilpotent singular support

Abstract

We define a stratification of the moduli stack of coherent sheaves on an elliptic curve which allows us (1) to give an explicit description of the irreducible components of the global nilpotent cone of elliptic curves, (2) to establish an explicit bijection between the simple objects of the category of perverse sheaves defined by Schiffmann to categorify the elliptic Hall algebra (the so-called spherical Eisenstein sheaves) and the irreducible components of the global nilpotent cone and (3) to give an explicit description and parametrization of the perverse sheaves on the moduli stack of coherent sheaves on an elliptic curve having nilpotent singular support. Along the way, we find a combinatorial parametrization of the irreducible components of the semistable locus of the elliptic global nilpotent cone.