Knot contact homology as a planar limit of Chern-Simons theory
Ben Webster, Meri Zaimi
TL;DR
The paper develops a skein-theoretic, Deligne-style planar-limit framework to connect the augmentation varieties of knots and links with the large-$N$ limit of Chern-Simons theory. It introduces the HOMFLYPT difference module as a module over a quantum torus, built from heavy and light objects in a planar limit of the HOMFLYPT spider category, and shows that its degree-0 classical limit recovers abelianized knot contact homology (KCH). The central result is an isomorphism between KCH and the planar-limit invariant $\mathsf{H}(K)$, with a conjectural identification of the augmentation ideal as the classical limit of the quantum-parameterized recursion ideal for colored HOMFLYPT polynomials, extending to links. Together these contributions provide an algebraic, skein-theoretic route to connecting knot contact geometry, HOMFLYPT recursions, and large-$N$ duality, with potential implications for understanding augmentation varieties and holonomic structures in knot theory.
Abstract
We prove a conjecture relating augmentation varieties to the large $N$ limit of Chern-Simons theory. Although this does not directly establish that the augmentation polynomial of a knot is the classical limit of a deformed $\hat{A}$-polynomial -- as suggested by Aganagić and Vafa -- it reduces the problem to characterizing certain algebraic properties of a module over the quantum torus, introduced in work of Gaiotto, Kannagi, and Sanjurjo. We term this the \emph{HOMFLYPT difference module}, which captures relations between the colored HOMFLYPT polynomials of different antisymmetric colorings. We demonstrate that the classical limit of this difference module for a knot is precisely the degree 0 abelianized knot contact homology of the knot, and we provide a natural extension of this result to links.
