Macdonald Identities, Weyl-Kac Denominator Formulas and Affine Grassmannian Elements

The Nekrasov-Okounkov formula gives an expression for the Fourier coefficients of the Euler functions as a sum of hook length products. This formula can be deduced from a specialization in a renormalization of the affine type Weyl denominator formula and the use of a polynomial argument. In this pa...

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Опубліковано в: :Symmetry, Integrability and Geometry: Methods and Applications
Дата:2025
Автори: Lecouvey, Cédric, Wahiche, David
Формат: Стаття
Мова:Англійська
Опубліковано: Інститут математики НАН України 2025
Онлайн доступ:https://nasplib.isofts.kiev.ua/handle/123456789/213190
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Назва журналу:Digital Library of Periodicals of National Academy of Sciences of Ukraine
Цитувати:Macdonald Identities, Weyl-Kac Denominator Formulas and Affine Grassmannian Elements. Cédric Lecouvey and David Wahiche. SIGMA 21 (2025), 023, 45 pages

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Digital Library of Periodicals of National Academy of Sciences of Ukraine
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author Lecouvey, Cédric
Wahiche, David
author_facet Lecouvey, Cédric
Wahiche, David
citation_txt Macdonald Identities, Weyl-Kac Denominator Formulas and Affine Grassmannian Elements. Cédric Lecouvey and David Wahiche. SIGMA 21 (2025), 023, 45 pages
collection DSpace DC
container_title Symmetry, Integrability and Geometry: Methods and Applications
description The Nekrasov-Okounkov formula gives an expression for the Fourier coefficients of the Euler functions as a sum of hook length products. This formula can be deduced from a specialization in a renormalization of the affine type Weyl denominator formula and the use of a polynomial argument. In this paper, we rephrase the renormalized Weyl-Kac denominator formula as a sum parametrized by affine Grassmannian elements. This naturally gives rise to the (dual) atomic length of the root system considered introduced by Chapelier-Laget and Gerber. We then provide an interpretation of this atomic length as the cardinality of some subsets of -core partitions by using foldings of affine Dynkin diagrams. This interpretation does not permit the direct use of a polynomial argument for all affine root systems. We show that this obstruction can be overcome by computing the atomic length of certain families of integer partitions. Then we show how hook-length statistics on these partitions are connected with the Coxeter length on affine Grassmannian elements and Nekrasov-Okounkov type formulas.
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last_indexed 2026-03-21T11:59:30Z
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publisher Інститут математики НАН України
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spelling Lecouvey, Cédric
Wahiche, David
2026-02-16T16:36:02Z
2025
Macdonald Identities, Weyl-Kac Denominator Formulas and Affine Grassmannian Elements. Cédric Lecouvey and David Wahiche. SIGMA 21 (2025), 023, 45 pages
1815-0659
2020 Mathematics Subject Classification: 05E05; 05E10; 11P81
arXiv:2404.10532
https://nasplib.isofts.kiev.ua/handle/123456789/213190
https://doi.org/10.3842/SIGMA.2025.023
The Nekrasov-Okounkov formula gives an expression for the Fourier coefficients of the Euler functions as a sum of hook length products. This formula can be deduced from a specialization in a renormalization of the affine type Weyl denominator formula and the use of a polynomial argument. In this paper, we rephrase the renormalized Weyl-Kac denominator formula as a sum parametrized by affine Grassmannian elements. This naturally gives rise to the (dual) atomic length of the root system considered introduced by Chapelier-Laget and Gerber. We then provide an interpretation of this atomic length as the cardinality of some subsets of -core partitions by using foldings of affine Dynkin diagrams. This interpretation does not permit the direct use of a polynomial argument for all affine root systems. We show that this obstruction can be overcome by computing the atomic length of certain families of integer partitions. Then we show how hook-length statistics on these partitions are connected with the Coxeter length on affine Grassmannian elements and Nekrasov-Okounkov type formulas.
The authors would like to thank the referees as well as the editors for their precious comments and suggestions to help this paper to be much clearer. The authors would also like to thank Olivier Brunat, Nathan Chapelier-Laget, Thomas Gerber, Igor Haladjian, Guo-Niu Han, and Ole Warnaar for their interest and their precious remarks, as well as Philippe Nadeau for suggesting the reformulation of Theorem 7.4. Both authors are supported by the Agence Nationale de la Recherche funding ANR CORTIPOM 21-CE40-001.
en
Інститут математики НАН України
Symmetry, Integrability and Geometry: Methods and Applications
Macdonald Identities, Weyl-Kac Denominator Formulas and Affine Grassmannian Elements
Article
published earlier
spellingShingle Macdonald Identities, Weyl-Kac Denominator Formulas and Affine Grassmannian Elements
Lecouvey, Cédric
Wahiche, David
title Macdonald Identities, Weyl-Kac Denominator Formulas and Affine Grassmannian Elements
title_full Macdonald Identities, Weyl-Kac Denominator Formulas and Affine Grassmannian Elements
title_fullStr Macdonald Identities, Weyl-Kac Denominator Formulas and Affine Grassmannian Elements
title_full_unstemmed Macdonald Identities, Weyl-Kac Denominator Formulas and Affine Grassmannian Elements
title_short Macdonald Identities, Weyl-Kac Denominator Formulas and Affine Grassmannian Elements
title_sort macdonald identities, weyl-kac denominator formulas and affine grassmannian elements
url https://nasplib.isofts.kiev.ua/handle/123456789/213190
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