Exact-WKB, complete resurgent structure, and mixed anomaly in quantum mechanics on $S^1$

TL;DR

This paper applies exact-WKB analysis to quantum mechanics on a circle with multiple minima, revealing a resurgent structure consistent with anomalies and providing a detailed understanding of quantization conditions and topological sectors.

Contribution

It introduces a comprehensive exact-WKB framework for periodic potentials on $S^1$, linking Stokes graphs, resurgence, and anomalies, and proves the closure of resurgent structures in topological sectors.

Findings

Quantization condition factorizes over theta sectors

Resurgent structure is closed within Hilbert subspaces

Consistent with mixed anomalies and global inconsistency

Abstract

We investigate the exact-WKB analysis for quantum mechanics in a periodic potential, with $N $ minima on $S^{1}$. We describe the Stokes graphs of a general potential problem as a network of Airy-type or degenerate Weber-type building blocks, and provide a dictionary between the two. The two formulations are equivalent, but with their own pros and cons. Exact-WKB produces the quantization condition consistent with the known conjectures and mixed anomaly. The quantization condition for the case of $N$-minima on the circle factorizes over the Hilbert sub-spaces labeled by discrete theta angle (or Bloch momenta), and is consistent with 't Hooft anomaly for even $N$ and global inconsistency for odd $N$. By using Delabaere-Dillinger-Pham formula, we prove that the resurgent structure is closed in these Hilbert subspaces, built on discrete theta vacua, and by a transformation, this implies that fixed topological sectors (columns of resurgence triangle) are also closed under resurgence.