English

Sections of Lagrangian fibrations on holomorphic symplectic manifolds

Algebraic Geometry 2025-10-17 v5 Complex Variables Differential Geometry

Abstract

Let MM be a holomorphically symplectic manifold, equipped with a Lagrangian fibration π:  MX\pi:\; M \to X. A degenerate twistor deformation (sometimes also called ``a Tate-Shafarevich twist'') is a family of holomorphically symplectic structures on MM parametrized by H1,1(X)H^{1,1}(X). All members of this family are equipped with a holomorphic Lagrangian projection to XX, and their fibers are isomorphic to the fibers of π\pi. Assume that MM is a compact hyperkahler manifold of maximal holonomy, and the general fiber of the Lagrangian projection π\pi is primitive (that is, not divisible) in integer homology. We also assume that π\pi has reduced fibers in codimension 1. Then MM has a degenerate twistor deformation MM' such that the Lagrangian projection π:  MX\pi:\; M' \to X admits a meromorphic section.

Keywords

Cite

@article{arxiv.2407.07877,
  title  = {Sections of Lagrangian fibrations on holomorphic symplectic manifolds},
  author = {Fedor Bogomolov and Ljudmila Kamenova and Misha Verbitsky},
  journal= {arXiv preprint arXiv:2407.07877},
  year   = {2025}
}

Comments

30 pages, v. 5.0, cleared some questions from J. Koll\'ar and G. Sacc\`a, a section split off into a separate paper (arXiv:2509.12369)