Mock modularity of log Gromov--Witten Invariants: the mirror to $\mathbb{P}^2$
Hülya Argüz
TL;DR
The article investigates the emergence of mock modular forms in the generating series of logarithmic Gromov–Witten invariants for elliptic fibrations relative to singular fibers, proposing that these series are mock modular and proving this for a broad class in the rational elliptic surface mirror to $\mathbb{P}^2$. It builds a bridge between log GW theory (via the Gross–Siebert program) and Vafa–Witten invariants, establishing a precise correspondence on the mirror pair that transfers modularity properties from VW to log GW counts. Concretely, it proves that the log GW generating series for the mirror $(Y,D)$ to $\mathbb{P}^2$ coincides with VW generating series in a regime, implying their mock modularity with weight $-\tfrac{3}{2}$ and depth matching the rank. The results provide a robust mathematical realization of VW-inspired mock modularity in log GW theory, and they predict deeper mock modular structures for higher ranks, connecting enumerative geometry, mirror symmetry, and four-dimensional gauge theory.
Abstract
We study modularity properties of generating series of logarithmic Gromov-Witten invariants of elliptic fibrations relative to singular fibers. Motivated by predictions from Vafa-Witten theory, we conjecture that such generating series are mock modular forms. We prove this conjecture for a large class of invariants of the rational elliptic surface mirror to $\mathbb{P}^2$, relative to a cycle of nine rational curves. The proof uses a correspondence between log Gromov-Witten invariants of the mirror and Vafa-Witten invariants of $\mathbb{P}^2$ established in previous work joint with Bousseau, together with known mock modularity results on the Vafa-Witten side.
