English

Lefschetz filtration and Perverse filtration on the compactified Jacobian

Algebraic Geometry 2026-03-10 v1

Abstract

Let CC be a complex integral curve with plannar singularities. Let JJ be the compactified Jacobian of CC. There are two filtrations on the cohomology group H(J)H^*(J). One is obtained by the nilpotent morphism defined by cupping a certain ample divisor on JJ, which we call the Lefschetz filtration. To obtain the other filtration, we put CC into a family of curves CB\mathcal{C}\rightarrow B so that JJ can be embedded into a family f:JBf:\mathcal{J}\rightarrow B, and we let B,C,JB, \mathcal{C},\mathcal{J} be smooth. Then Rf(QJ)Rf_*(\mathbb{Q}_{\mathcal{J}}) decomposes into a direct sum of its (shifted) perverse cohomologies. Restricting this decomposition to fibers, we get a filtration on H(J)H^*(J) called the perverse filtration. We show in this paper that these two filtrations are opposite to each other as conjectured by Maulik-Yun.

Keywords

Cite

@article{arxiv.2603.07193,
  title  = {Lefschetz filtration and Perverse filtration on the compactified Jacobian},
  author = {Yao Yuan},
  journal= {arXiv preprint arXiv:2603.07193},
  year   = {2026}
}