English

Extremal Lagrangian tori in toric domains

Symplectic Geometry 2026-05-29 v2 Differential Geometry

Abstract

Let LL be a closed Lagrangian submanifold of a symplectic manifold (X,ω)(X,\omega). Cieliebak and Mohnke define the symplectic area of LL as the minimal positive symplectic area of a smooth 22-disk in XX with boundary on LL. An extremal Lagrangian torus in (X,ω)(X,\omega) is a Lagrangian torus that maximizes the symplectic area among the Lagrangian tori in (X,ω)(X,\omega). We prove that every extremal Lagrangian torus in the symplectic unit ball (Bˉ2n(1),ωstd)(\bar{B}^{2n}(1),\omega_{\mathrm{std}}) is contained entirely in the boundary B2n(1)\partial B^{2n}(1). This answers a question attributed to Lazzarini and completely settles a conjecture of Cieliebak and Mohnke in the affirmative. In addition, we prove the conjecture for a class of toric domains in (Cn,ωstd)(\mathbb{C}^n, \omega_{\mathrm{std}}), which includes all compact strictly convex four-dimensional toric domains. We explain with counterexamples that the general conjecture does not hold for non-convex domains.

Keywords

Cite

@article{arxiv.2504.13076,
  title  = {Extremal Lagrangian tori in toric domains},
  author = {Shah Faisal},
  journal= {arXiv preprint arXiv:2504.13076},
  year   = {2026}
}

Comments

93 pages, 12 figures. Revised version incorporating the referee's suggestions and comments