Cusped hyperbolic Lagrangians as mirrors to lines in three-space
Sebastian Haney
TL;DR
The paper constructs a singular Lagrangian lift of a 4-valent tropical vertex inside $T^*T^3$, whose smooth part is the minimally twisted five-component chain link complement, and then forms an immersed Lagrangian via a doubling trick. It develops an immersed Wrapped Floer theory to define a wrapped Fukaya category for such objects, analyzes obstructions, gradings, and unobstructedness, and shows that for generic lines in $P^3$, there exists a local system making the wrapped Floer object mirror to a line in the mirror. A tropical Lagrangian lift framework is used to relate the Floer-theoretic data to very affine lines, with the Grassmann–Plücker relations encoding the necessary compatibility conditions. The work also develops desingularizations and smoothings of the singular lift, as well as a framework for immersions that may inform future mirror symmetry statements for lines in Calabi–Yau threefolds, including the quintic mirror.
Abstract
We construct a Lagrangian in the cotangent bundle of a 3-torus whose projection to the fiber is a neighborhood of a tropical curve with a single 4-valent vertex. This Lagrangian has an isolated conical singular point, and its smooth locus is diffeomorphic to the minimally-twisted five component chain link complement, a cusped hyperbolic 3-manifold. From this singular Lagrangian, we construct an immersed Lagrangian, and determine when it is unobstructed in the wrapped Fukaya category. We show that for a generic line in projective 3-space, there is a local system on this immersed Lagrangian such that the resulting object of the wrapped Fukaya category is homologically mirror to an object of the derived category supported on the line. In the course of the proof, we construct a version of the wrapped Fukaya category with objects supported on Lagrangian immersions, which may be of independent interest.
