Quasimaps to moduli spaces of sheaves
Denis Nesterov
TL;DR
This work develops a comprehensive theory of quasimaps to moduli spaces of sheaves on a surface, proving that their moduli are proper and carry perfect obstruction theories, and establishes a canonical correspondence with moduli of sheaves on threefolds $S\times C$. By transporting quasimaps to a sheaf-theoretic framework, the authors derive wall-crossing formulas that relate the Gromov–Witten theory of $M(\mathbf{v})$ to Donaldson–Thomas theory of $S\times C$ with relative insertions, with explicit computations in the Hilbert-schemes case when $S$ is a del Pezzo surface. The paper further develops the determinant-line-bundle apparatus, stability notions (including $\epsilon$-stability), and an array of equivalences between quasimap moduli and relative moduli spaces of sheaves, including perverse-heart perspectives and stable-pair reformulations. A significant portion is devoted to Hilbert schemes, their ideal-sheaf interpretation, and the resulting $I$-function (vertex) framework, enabling concrete wall-crossing and computations that connect GW, DT, and PT theories in various geometries. Overall, the work builds a bridge between quasimap theory and DT/PT/GW correspondences, providing a robust toolkit for calculating invariants in surface- and threefold-derived settings and guiding future explorations on K3 and toric del Pezzo geometries.
Abstract
We develop a theory of quasimaps to a moduli space of sheaves $M$ on a surface $S$. Under some assumptions, we prove that moduli spaces of quasimaps are proper and carry a perfect obstruction theory. Moreover, they are naturally isomorphic to moduli spaces of sheaves on threefolds $S\times C$, where $C$ is a nodal curve. Using Zhou's theory of entangled tails, we establish a wall-crossing formula which therefore relates the Gromov-Witten theory of $M$ and the Donaldson-Thomas theory of $S\times C$ with relative insertions. We evaluate the wall-crossing formula for Hilbert schemes of points $S^{[n]}$, if $S$ is a del Pezzo surface.
