Geometrization of the Satake transform for mod p Hecke algebras

We geometrize the mod p Satake isomorphism of Herzig and Henniart–Vignéras using Witt vector affine flag varieties for reductive groups in mixed characteristic. We deduce this as a special case of a formula, stated in terms of the geometry of generalized Mirković–Vilonen cycles, for the Satake trans...

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Main Authors: Robert Cass, Yujie Xu
Format: Article
Language:English
Published: Cambridge University Press 2025-01-01
Series:Forum of Mathematics, Sigma
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Online Access:https://www.cambridge.org/core/product/identifier/S2050509424001300/type/journal_article
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author Robert Cass
Yujie Xu
author_facet Robert Cass
Yujie Xu
author_sort Robert Cass
collection DOAJ
description We geometrize the mod p Satake isomorphism of Herzig and Henniart–Vignéras using Witt vector affine flag varieties for reductive groups in mixed characteristic. We deduce this as a special case of a formula, stated in terms of the geometry of generalized Mirković–Vilonen cycles, for the Satake transform of an arbitrary parahoric mod p Hecke algebra with respect to an arbitrary Levi subgroup. Moreover, we prove an explicit formula for the convolution product in an arbitrary parahoric mod p Hecke algebra. Our methods involve the constant term functors inspired from the geometric Langlands program, and we also treat the case of reductive groups in equal characteristic. We expect this to be a first step toward a geometrization of a mod p Local Langlands Correspondence.
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institution Kabale University
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series Forum of Mathematics, Sigma
spelling doaj-art-5ebd17e2d3244378a8d78963e80b33652025-02-05T07:57:33ZengCambridge University PressForum of Mathematics, Sigma2050-50942025-01-011310.1017/fms.2024.130Geometrization of the Satake transform for mod p Hecke algebrasRobert Cass0https://orcid.org/0000-0003-2242-5758Yujie Xu1https://orcid.org/0000-0003-3023-3609University of Michigan, 530 Church St, Ann Arbor, MI 48109, U.S.A.Columbia University, 2990 Broadway, New York, NY 10027, U.S.A.; E-mail:We geometrize the mod p Satake isomorphism of Herzig and Henniart–Vignéras using Witt vector affine flag varieties for reductive groups in mixed characteristic. We deduce this as a special case of a formula, stated in terms of the geometry of generalized Mirković–Vilonen cycles, for the Satake transform of an arbitrary parahoric mod p Hecke algebra with respect to an arbitrary Levi subgroup. Moreover, we prove an explicit formula for the convolution product in an arbitrary parahoric mod p Hecke algebra. Our methods involve the constant term functors inspired from the geometric Langlands program, and we also treat the case of reductive groups in equal characteristic. We expect this to be a first step toward a geometrization of a mod p Local Langlands Correspondence.https://www.cambridge.org/core/product/identifier/S2050509424001300/type/journal_article14D2420C0814M15
spellingShingle Robert Cass
Yujie Xu
Geometrization of the Satake transform for mod p Hecke algebras
Forum of Mathematics, Sigma
14D24
20C08
14M15
title Geometrization of the Satake transform for mod p Hecke algebras
title_full Geometrization of the Satake transform for mod p Hecke algebras
title_fullStr Geometrization of the Satake transform for mod p Hecke algebras
title_full_unstemmed Geometrization of the Satake transform for mod p Hecke algebras
title_short Geometrization of the Satake transform for mod p Hecke algebras
title_sort geometrization of the satake transform for mod p hecke algebras
topic 14D24
20C08
14M15
url https://www.cambridge.org/core/product/identifier/S2050509424001300/type/journal_article
work_keys_str_mv AT robertcass geometrizationofthesataketransformformodpheckealgebras
AT yujiexu geometrizationofthesataketransformformodpheckealgebras