The Ising Model Coupled to 2D Gravity: Genus Zero Partition Function

We compute the genus 0 free energy for the 2-matrix model with quartic interactions, which acts as a generating function for the Ising model's partition function on a random, 4-regular, planar graph. This is consistent with the predictions of Kazakov and Boulatov on this model, as well as subse...

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Published in:Symmetry, Integrability and Geometry: Methods and Applications
Date:2025
Main Authors: Duits, Maurice, Hayford, Nathan, Lee, Seung-Yeop
Format: Article
Language:English
Published: Інститут математики НАН України 2025
Online Access:https://nasplib.isofts.kiev.ua/handle/123456789/214089
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Journal Title:Digital Library of Periodicals of National Academy of Sciences of Ukraine
Cite this:The Ising Model Coupled to 2D Gravity: Genus Zero Partition Function. Maurice Duits, Nathan Hayford and Seung-Yeop Lee. SIGMA 21 (2025), 079, 90 pages

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Digital Library of Periodicals of National Academy of Sciences of Ukraine
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author Duits, Maurice
Hayford, Nathan
Lee, Seung-Yeop
author_facet Duits, Maurice
Hayford, Nathan
Lee, Seung-Yeop
citation_txt The Ising Model Coupled to 2D Gravity: Genus Zero Partition Function. Maurice Duits, Nathan Hayford and Seung-Yeop Lee. SIGMA 21 (2025), 079, 90 pages
collection DSpace DC
container_title Symmetry, Integrability and Geometry: Methods and Applications
description We compute the genus 0 free energy for the 2-matrix model with quartic interactions, which acts as a generating function for the Ising model's partition function on a random, 4-regular, planar graph. This is consistent with the predictions of Kazakov and Boulatov on this model, as well as subsequent confirmation of this formula using combinatorial methods. We also provide a new parametric formula for the free energy and give a characterization of the phase space. Our analysis is based on a steepest descent Riemann-Hilbert analysis of the associated biorthogonal polynomials and the corresponding isomonodromic τ-function. A key ingredient in the analysis is a parametrization of the spectral curve. This analysis lays the groundwork for the subsequent study of the multicritical point, which we will study in a forthcoming work.
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spelling Duits, Maurice
Hayford, Nathan
Lee, Seung-Yeop
2026-02-19T11:09:22Z
2025
The Ising Model Coupled to 2D Gravity: Genus Zero Partition Function. Maurice Duits, Nathan Hayford and Seung-Yeop Lee. SIGMA 21 (2025), 079, 90 pages
1815-0659
2020 Mathematics Subject Classification: 30E15; 30E10; 30E25; 41A60; 05C30; 05C10
arXiv:2405.03259
https://nasplib.isofts.kiev.ua/handle/123456789/214089
https://doi.org/10.3842/SIGMA.2025.079
We compute the genus 0 free energy for the 2-matrix model with quartic interactions, which acts as a generating function for the Ising model's partition function on a random, 4-regular, planar graph. This is consistent with the predictions of Kazakov and Boulatov on this model, as well as subsequent confirmation of this formula using combinatorial methods. We also provide a new parametric formula for the free energy and give a characterization of the phase space. Our analysis is based on a steepest descent Riemann-Hilbert analysis of the associated biorthogonal polynomials and the corresponding isomonodromic τ-function. A key ingredient in the analysis is a parametrization of the spectral curve. This analysis lays the groundwork for the subsequent study of the multicritical point, which we will study in a forthcoming work.
MD was supported by the Swedish Research Council (VR), grant no. 2021-06015, and the European Research Council (ERC), Grant Agreement No. 101002013. NH was supported by the European Research Council (ERC), Grant Agreement No. 101002013. Part of the work was completed while NH was at the University of South Florida. We would like to thank an anonymous referee, who pointed out some results in the literature that rigorously derive the genus-zero free energy using combinatorial methods. We would also like to thank all of the referees, whose valuable comments helped improve the overall presentation of this manuscript.
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Інститут математики НАН України
Symmetry, Integrability and Geometry: Methods and Applications
The Ising Model Coupled to 2D Gravity: Genus Zero Partition Function
Article
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spellingShingle The Ising Model Coupled to 2D Gravity: Genus Zero Partition Function
Duits, Maurice
Hayford, Nathan
Lee, Seung-Yeop
title The Ising Model Coupled to 2D Gravity: Genus Zero Partition Function
title_full The Ising Model Coupled to 2D Gravity: Genus Zero Partition Function
title_fullStr The Ising Model Coupled to 2D Gravity: Genus Zero Partition Function
title_full_unstemmed The Ising Model Coupled to 2D Gravity: Genus Zero Partition Function
title_short The Ising Model Coupled to 2D Gravity: Genus Zero Partition Function
title_sort ising model coupled to 2d gravity: genus zero partition function
url https://nasplib.isofts.kiev.ua/handle/123456789/214089
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