Punctual Hilbert schemes for Kleinian singularities as quiver varieties

Abstract

For a finite subgroup $\Gamma \subset \mathrm{SL}(2,\mathbb{C})$ and $n\ge 1$, we construct the (reduced scheme underlying the) Hilbert scheme of $n$ points on the Kleinian singularity ${\mathbb{C}}^2/\Gamma$ as a Nakajima quiver variety for the framed McKay quiver of $\Gamma$, taken at a specific non-generic stability parameter. We deduce that this Hilbert scheme is irreducible (a result previously due to Zheng), normal, and admits a unique symplectic resolution. More generally, we introduce a class of algebras obtained from the preprojective algebra of the framed McKay quiver by a process called cornering, and we show that fine moduli spaces of cyclic modules over these new algebras are isomorphic to quiver varieties for the framed McKay quiver and certain non-generic choices of stability parameter.

24 pages. v3: Definition of cornered algebras simplified. To be published in Algebraic Geometry