Cohomological $χ$-independence for Higgs bundles and Gopakumar-Vafa invariants
Tasuki Kinjo, Naoki Koseki
TL;DR
The paper proves χ-independence for Gopakumar–Vafa invariants of local curves using a global d-critical chart description that recasts moduli spaces as critical loci, and introduces BPS cohomology for Dolbeault moduli with noncoprime χ, showing χ-independence via mixed Hodge module isomorphisms on the Hitchin base. It develops a cohomological integrality framework for twisted Higgs bundles, including an approximation-by-proper-morphisms method and monodromic mixed Hodge modules, yielding a symmetric-product decomposition of vanishing-cycle data. The Higgs-bundle case is then analyzed through dimensional reduction, establishing χ-independence and integrality for BPS cohomology, with explicit examples illustrating differences between intersection cohomology and BPS cohomology in noncoprime settings. Together, these results extend P=W-type phenomena to broader noncoprime contexts, provide a unifying cohomological perspective on GV/BPS invariants, and deepen the link between curve counting and Higgs-bundle moduli via d-critical geometry and mixed Hodge theory.
Abstract
The aim of this paper is two-fold: Firstly, we prove Toda's $χ$-independence conjecture for Gopakumar--Vafa invariants of arbitrary local curves. Secondly, following Davison's work, we introduce the BPS cohomology for moduli spaces of Higgs bundles of rank $r$ and Euler characteristic $χ$ which are not necessary coprime, and show that it does not depend on $χ$. This result extends the Hausel--Thaddeus conjecture on the $χ$-independence of E-polynomials proved by Mellit, Groechenig--Wyss--Ziegler and Yu in two ways: we obtain an isomorphism of mixed Hodge modules on the Hitchin base rather than an equality of E-polynomials, and we do not need the coprime assumption. The proof of these results is based on a description of the moduli stack of one-dimensional coherent sheaves on a local curve as a global critical locus which is obtained in the companion paper by the first author and Naruki Masuda.
