English

Finiteness for Hecke algebras of $p$-adic groups

Representation Theory 2022-04-25 v2

Abstract

Let GG be a reductive group over a non-archimedean local field FF of residue characteristic pp. We prove that the Hecke algebras of G(F)G(F) with coefficients in a Z{\mathbb Z}_{\ell}-algebra RR for \ell not equal to pp are finitely generated modules over their centers, and that these centers are finitely generated RR-algebras. Following Bernstein's original strategy, we then deduce that "second adjointness" holds for smooth representations of G(F)G(F) with coefficients in any ring RR in which pp is invertible. These results had been conjectured for a long time. The crucial new tool that unlocks the problem is the Fargues-Scholze morphism between a certain "excursion algebra" defined on the Langlands parameters side and the Bernstein center of G(F)G(F). Using this bridge, our main results are representation theoretic counterparts of the finiteness of certain morphisms between coarse moduli spaces of local Langlands parameters that we also prove here, which may be of independent interest

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Cite

@article{arxiv.2203.04929,
  title  = {Finiteness for Hecke algebras of $p$-adic groups},
  author = {Jean-Francois Dat and David Helm and Robert Kurinczuk and Gilbert Moss},
  journal= {arXiv preprint arXiv:2203.04929},
  year   = {2022}
}

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16 pages