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Revisiting the Quantum Geometry of Torus-fibered Calabi-Yau Threefolds

by Boris Pioline, Thorsten Schimannek

Submission summary

Authors (as registered SciPost users): Thorsten Schimannek
Submission information
Preprint Link: scipost_202601_00060v1  (pdf)
Date submitted: Jan. 26, 2026, 10:10 a.m.
Submitted by: Thorsten Schimannek
Submitted to: SciPost Physics
Ontological classification
Academic field: Physics
Specialties:
  • High-Energy Physics - Theory
Approaches: Theoretical, Computational

Abstract

About ten years ago, Katz, Klemm and Huang conjectured that topological string amplitudes on compact, elliptically fibered Calabi-Yau threefolds at fixed base degree could be expressed in terms of meromorphic Jacobi forms for SL(2,ℤ), giving access to Gromov-Witten invariants at arbitrary genus. This was later generalized to torus-fibered CY threefolds with N-sections, where topological string amplitudes are conjecturally governed by meromorphic Jacobi forms under the congruence subgroup Γ1(N). In this work, we show that these modularity properties follow from (and are equivalent to) the wave-function property of the topological string partition function Ztop under a relative conifold monodromy, implementing a particular Fourier-Mukai transformation on the derived category of coherent sheaves. In particular, we introduce a variant of Ztop which is both holomorphic and modular covariant. Under the same relative conifold monodromy, the generating series of genus 0 Gopakumar-Vafa invariants at fixed base degree is mapped to the generating series of rank 0 Donaldson-Thomas indices counting D4-D2-D0-brane bound states wrapped on the torus fiber. We show that the quasimodularity of the generating series of GV invariants matches the expected mock-modular behavior of the generating series of D4-D2-D0 indices, despite having different multi-cover contributions. We analyze and tabulate a large number of CY threefolds fibered over del Pezzo surfaces, with an N-section for N≤5, including several new examples beyond the realm of toric geometry.

Author indications on fulfilling journal expectations

  • Provide a novel and synergetic link between different research areas.
  • Open a new pathway in an existing or a new research direction, with clear potential for multi-pronged follow-up work
  • Detail a groundbreaking theoretical/experimental/computational discovery
  • Present a breakthrough on a previously-identified and long-standing research stumbling block
Current status:
In refereeing

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