Aspects of Hecke Symmetry: Anomalies, Curves, and Chazy Equations

We study various relations governing quasi-automorphic forms associated with discrete subgroups of SL(2, ℝ), namely the Hecke groups. We show that the Eisenstein series associated to a Hecke group H(m) satisfy a set of m coupled linear differential equations, which are natural analogues of the well-...

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Published in:Symmetry, Integrability and Geometry: Methods and Applications
Date:2020
Main Authors: Ashok, Sujay K., Jatkar, Dileep P., Raman, Madhusudhan
Format: Article
Language:English
Published: Інститут математики НАН України 2020
Online Access:https://nasplib.isofts.kiev.ua/handle/123456789/210609
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Journal Title:Digital Library of Periodicals of National Academy of Sciences of Ukraine
Cite this:Aspects of Hecke Symmetry: Anomalies, Curves, and Chazy Equations. Sujay K. Ashok, Dileep P. Jatkar and Madhusudhan Raman. SIGMA 16 (2020), 001, 26 pages

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Digital Library of Periodicals of National Academy of Sciences of Ukraine
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author Ashok, Sujay K.
Jatkar, Dileep P.
Raman, Madhusudhan
author_facet Ashok, Sujay K.
Jatkar, Dileep P.
Raman, Madhusudhan
citation_txt Aspects of Hecke Symmetry: Anomalies, Curves, and Chazy Equations. Sujay K. Ashok, Dileep P. Jatkar and Madhusudhan Raman. SIGMA 16 (2020), 001, 26 pages
collection DSpace DC
container_title Symmetry, Integrability and Geometry: Methods and Applications
description We study various relations governing quasi-automorphic forms associated with discrete subgroups of SL(2, ℝ), namely the Hecke groups. We show that the Eisenstein series associated to a Hecke group H(m) satisfy a set of m coupled linear differential equations, which are natural analogues of the well-known Ramanujan identities for quasi-modular forms of SL(2, ℤ). Each Hecke group is then associated with a (hyper-)elliptic curve, whose coefficients are determined by an anomaly equation. For the m = 3 and 4 cases, the Ramanujan identities admit a natural geometric interpretation as a Gauss-Manin connection on the parameter space of the elliptic curve. The Ramanujan identities also allow us to associate a nonlinear differential equation of order m to each Hecke group. These equations are higher-order analogues of the Chazy equation, and we show that they are solved by the quasi-automorphic Eisenstein series E⁽ᵐ⁾₂ associated to H(m) and its orbit under the Hecke group. We conclude by demonstrating that these nonlinear equations possess the Painlevé property.
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institution Digital Library of Periodicals of National Academy of Sciences of Ukraine
issn 1815-0659
language English
last_indexed 2025-12-17T12:04:20Z
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spelling Ashok, Sujay K.
Jatkar, Dileep P.
Raman, Madhusudhan
2025-12-12T10:41:57Z
2020
Aspects of Hecke Symmetry: Anomalies, Curves, and Chazy Equations. Sujay K. Ashok, Dileep P. Jatkar and Madhusudhan Raman. SIGMA 16 (2020), 001, 26 pages
1815-0659
2010 Mathematics Subject Classification: 34M55; 11F12; 33E30
arXiv:1810.07919
https://nasplib.isofts.kiev.ua/handle/123456789/210609
https://doi.org/10.3842/SIGMA.2020.001
We study various relations governing quasi-automorphic forms associated with discrete subgroups of SL(2, ℝ), namely the Hecke groups. We show that the Eisenstein series associated to a Hecke group H(m) satisfy a set of m coupled linear differential equations, which are natural analogues of the well-known Ramanujan identities for quasi-modular forms of SL(2, ℤ). Each Hecke group is then associated with a (hyper-)elliptic curve, whose coefficients are determined by an anomaly equation. For the m = 3 and 4 cases, the Ramanujan identities admit a natural geometric interpretation as a Gauss-Manin connection on the parameter space of the elliptic curve. The Ramanujan identities also allow us to associate a nonlinear differential equation of order m to each Hecke group. These equations are higher-order analogues of the Chazy equation, and we show that they are solved by the quasi-automorphic Eisenstein series E⁽ᵐ⁾₂ associated to H(m) and its orbit under the Hecke group. We conclude by demonstrating that these nonlinear equations possess the Painlevé property.
We would like to thank Suresh Govindarajan for the discussions and for the collaboration during an early stage of the project. We also thank Renjan John for helpful comments on an earlier version of the manuscript, and the anonymous referees for valuable comments and feedback. MR acknowledges support from the Infosys Endowment for Research into the Quantum Structure of Spacetime. This research was supported in part by the International Centre for Theoretical Sciences (ICTS) during a visit to participate in the program Quantum Fields, Geometry and Representation Theory (Code: ICTS/qftgrt/2018/07).
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Інститут математики НАН України
Symmetry, Integrability and Geometry: Methods and Applications
Aspects of Hecke Symmetry: Anomalies, Curves, and Chazy Equations
Article
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spellingShingle Aspects of Hecke Symmetry: Anomalies, Curves, and Chazy Equations
Ashok, Sujay K.
Jatkar, Dileep P.
Raman, Madhusudhan
title Aspects of Hecke Symmetry: Anomalies, Curves, and Chazy Equations
title_full Aspects of Hecke Symmetry: Anomalies, Curves, and Chazy Equations
title_fullStr Aspects of Hecke Symmetry: Anomalies, Curves, and Chazy Equations
title_full_unstemmed Aspects of Hecke Symmetry: Anomalies, Curves, and Chazy Equations
title_short Aspects of Hecke Symmetry: Anomalies, Curves, and Chazy Equations
title_sort aspects of hecke symmetry: anomalies, curves, and chazy equations
url https://nasplib.isofts.kiev.ua/handle/123456789/210609
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AT ramanmadhusudhan aspectsofheckesymmetryanomaliescurvesandchazyequations