A proof of Witten's asymptotic expansion conjecture for WRT invariants of Seifert fibered homology spheres
Jørgen Ellegaard Andersen, Li Han, Yong Li, William Elbæk Mistegård, David Sauzin, Shanzhong Sun
TL;DR
This paper proves Witten's asymptotic expansion conjecture for SU(2) WRT invariants of Seifert fibered integral homology spheres with at least three exceptional fibers by linking WRT values at roots of unity to non-tangential limits of the GPPV invariant via a resurgence- and quantum-modular-form framework. The authors develop a detailed decomposition of the GPPV invariant into Hikami-function components, establish higher-depth quantum modularity, and connect to the Habiro invariant analytically. A new parametrization of the SU(2) moduli space on the orbifold surface is used to identify Chern-Simons invariants and to bound the growth of leading terms, enabling a rigorous Puiseux expansion for WRT invariants. The approach hinges on resurgent analysis, median sums, and a careful analysis of partial theta series, yielding a complete proof for all Seifert fibered integral homology spheres and clarifying the interplay between nonperturbative invariants and semiclassical data. This provides a solid bridge between quantum invariants, modularity phenomena, and gauge-theoretic moduli, with implications for semi-classical approximations and Habiro-type invariants.
Abstract
Let $X$ be a general Seifert fibered integral homology $3$-sphere with $r\ge3$ exceptional fibers. For every root of unity $ζ\not=1$, we show that the SU(2) WRT invariant of $X$ evaluated at $ζ$ is (up to an elementary factor) the non-tangential limit at $ζ$ of the GPPV invariant of $X$, thereby generalizing a result from [Andersen-Mistegard 2022]. Based on this result, we apply the quantum modularity results developed in [Han-Li-Sauzin-Sun 2023] to the GPPV invariant of $X$ to prove Witten's asymptotic expansion conjecture [Witten 1989] for the WRT invariant of $X$. We also prove that the GPPV invariant of $X$ induces a higher depth strong quantum modular form. Moreover, when suitably normalized, the GPPV invariant provides an ``analytic incarnation'' of the Habiro invariant.
