Perverse filtrations and Fourier transforms

TL;DR

This paper explores the relationship between Fourier-Mukai transforms and perverse filtrations in abelian fibrations, leading to proofs of several conjectures and new insights into the structure of these geometric objects.

Contribution

It introduces a new framework linking Fourier transforms and perverse filtrations, proving the motivic decomposition conjecture and the P=W and P=C conjectures for specific classes of fibrations.

Findings

Proved the motivic decomposition conjecture for certain abelian fibrations.

Provided a new proof of the P=W conjecture for GL_r.

Established the multiplicativity of the perverse filtration for compactified Jacobians.

Abstract

We study the interaction between Fourier-Mukai transforms and perverse filtrations for a certain class of dualizable abelian fibrations. Multiplicativity of the perverse filtration and the "Perverse $\supset$ Chern" phenomenon for these abelian fibrations are immediate consequences of our theory. We also show that our class of fibrations include families of compactified Jacobians of integral locally planar curves. Applications include the following: (a) we prove the motivic decomposition conjecture for this class (including compactified Jacobian fibrations), which generalizes Deninger-Murre's theorem for abelian schemes; (b) we provide a new proof of the P=W conjecture for $\mathrm{GL}_r$; (c) we prove half of the P=C conjecture concerning refined BPS invariants for the local $\mathbb{P}^2$; (d) we show that the perverse filtration for the compactified Jacobian associated with an integral locally planar curve is multiplicative, which generalizes a result of Oblomkov-Yun for homogeneous singularities. Our techniques combine Arinkin's autoduality for coherent categories, Ng\^o's support theorem for the decomposition theorem, Adams operations in operational K-theory, and Corti-Hanamura's theory of relative Chow motives.