₂ Invariants of Hourglass Chains via Quadratic Denominator Reduction

We introduce families of four-regular graphs consisting of chains of hourglasses which are attached to a finite kernel. We prove a formula for the ₂ invariant of these hourglass chains, which only depends on the kernel. For different kernels, these hourglass chains typically give rise to different ₂...

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Published in:Symmetry, Integrability and Geometry: Methods and Applications
Date:2021
Main Authors: Schnetz, Oliver, Yeats, Karen
Format: Article
Language:English
Published: Інститут математики НАН України 2021
Online Access:https://nasplib.isofts.kiev.ua/handle/123456789/211427
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Journal Title:Digital Library of Periodicals of National Academy of Sciences of Ukraine
Cite this:₂ Invariants of Hourglass Chains via Quadratic Denominator Reduction. Oliver Schnetz and Karen Yeats. SIGMA 17 (2021), 100, 26 pages

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Digital Library of Periodicals of National Academy of Sciences of Ukraine
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author Schnetz, Oliver
Yeats, Karen
author_facet Schnetz, Oliver
Yeats, Karen
citation_txt ₂ Invariants of Hourglass Chains via Quadratic Denominator Reduction. Oliver Schnetz and Karen Yeats. SIGMA 17 (2021), 100, 26 pages
collection DSpace DC
container_title Symmetry, Integrability and Geometry: Methods and Applications
description We introduce families of four-regular graphs consisting of chains of hourglasses which are attached to a finite kernel. We prove a formula for the ₂ invariant of these hourglass chains, which only depends on the kernel. For different kernels, these hourglass chains typically give rise to different ₂ invariants. An exhaustive search for the ₂ invariants of hourglass chains with kernels that have a maximum of ten vertices provides Calabi-Yau manifolds with point-counts which match the Fourier coefficients of modular forms whose weights and levels are [4,8], [4,16], [6,4], and [9,4]. Assuming the completion conjecture, we show that no modular form of weight 2 and level ≤ 1000 corresponds to the ₂ of such hourglass chains. This provides further evidence in favour of the conjecture that curves are absent in ₂ invariants of ⁴ quantum field theory.
first_indexed 2026-03-13T21:15:07Z
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institution Digital Library of Periodicals of National Academy of Sciences of Ukraine
issn 1815-0659
language English
last_indexed 2026-03-13T21:15:07Z
publishDate 2021
publisher Інститут математики НАН України
record_format dspace
spelling Schnetz, Oliver
Yeats, Karen
2026-01-02T08:30:47Z
2021
₂ Invariants of Hourglass Chains via Quadratic Denominator Reduction. Oliver Schnetz and Karen Yeats. SIGMA 17 (2021), 100, 26 pages
1815-0659
2020 Mathematics Subject Classification: 81T18
arXiv:2102.12383
https://nasplib.isofts.kiev.ua/handle/123456789/211427
https://doi.org/10.3842/SIGMA.2021.100
We introduce families of four-regular graphs consisting of chains of hourglasses which are attached to a finite kernel. We prove a formula for the ₂ invariant of these hourglass chains, which only depends on the kernel. For different kernels, these hourglass chains typically give rise to different ₂ invariants. An exhaustive search for the ₂ invariants of hourglass chains with kernels that have a maximum of ten vertices provides Calabi-Yau manifolds with point-counts which match the Fourier coefficients of modular forms whose weights and levels are [4,8], [4,16], [6,4], and [9,4]. Assuming the completion conjecture, we show that no modular form of weight 2 and level ≤ 1000 corresponds to the ₂ of such hourglass chains. This provides further evidence in favour of the conjecture that curves are absent in ₂ invariants of ⁴ quantum field theory.
Both authors are deeply indebted to Dirk Kreimer for many years of encouragement and support. Oliver Schnetz is supported by a DFG grant SCHN 1240. Karen Yeats is supported by an NSERC Discovery grant and by the Canada Research Chairs program; during some of this work, she was visiting Germany as a Humboldt fellow.
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Інститут математики НАН України
Symmetry, Integrability and Geometry: Methods and Applications
₂ Invariants of Hourglass Chains via Quadratic Denominator Reduction
Article
published earlier
spellingShingle ₂ Invariants of Hourglass Chains via Quadratic Denominator Reduction
Schnetz, Oliver
Yeats, Karen
title ₂ Invariants of Hourglass Chains via Quadratic Denominator Reduction
title_full ₂ Invariants of Hourglass Chains via Quadratic Denominator Reduction
title_fullStr ₂ Invariants of Hourglass Chains via Quadratic Denominator Reduction
title_full_unstemmed ₂ Invariants of Hourglass Chains via Quadratic Denominator Reduction
title_short ₂ Invariants of Hourglass Chains via Quadratic Denominator Reduction
title_sort ₂ invariants of hourglass chains via quadratic denominator reduction
url https://nasplib.isofts.kiev.ua/handle/123456789/211427
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AT yeatskaren 2invariantsofhourglasschainsviaquadraticdenominatorreduction