English

Resurgent Lambert series with characters

Number Theory 2025-07-30 v1 High Energy Physics - Theory

Abstract

We consider certain Lambert series as generating functions of divisor sums twisted by Dirichlet characters and compute their exact resurgent transseries expansion near q=1q=1^-. For special values of the parameters, these Lambert series are expressible in terms of iterated integrals of holomorphic Eisenstein series twisted by the same characters and the transseries representation is a direct consequence of the action of Fricke involution on such twisted Eisenstein series. When the parameters of the Lambert series are generic the transseries representation provides for a quantum-modular version of Fricke involution which for a particular example we show being equivalent to modular resurgent structures found in topological strings observables.

Keywords

Cite

@article{arxiv.2507.21352,
  title  = {Resurgent Lambert series with characters},
  author = {David Broadhurst and Daniele Dorigoni},
  journal= {arXiv preprint arXiv:2507.21352},
  year   = {2025}
}

Comments

50 pages plus appendices

R2 v1 2026-07-01T04:23:05.471Z