English

Compatibility of Kazhdan and Brauer homomorphism

Representation Theory 2025-02-19 v4

Abstract

Let GG be a connected split reductive group defined over Z\mathbb{Z}. Let FF and FF' be two non-Archimedean mm-close local fields, where mm is a positive integer. D.Kazhdan gave an isomorphism between the Hecke algebras KazmF:H(G(F),KF)H(G(F),KF){\rm Kaz}_m^F :\mathcal{H}\big(G(F),K_F\big) \rightarrow \mathcal{H}\big(G(F'),K_{F'}\big), where KFK_F and KFK_{F'} are the mm-th usual congruence subgroups of G(F)G(F) and G(F)G(F') respectively. On the other hand, if σ\sigma is an automorphism of GG of prime order ll, then we have Brauer homomorphism Br:H(G(F),U(F))H(Gσ(F),Uσ(F)){\rm Br}:\mathcal{H}(G(F),U(F))\rightarrow \mathcal{H}(G^\sigma(F),U^\sigma(F)), where U(F)U(F) and Uσ(F)U^\sigma(F) are compact open subgroups of G(F)G(F) and Gσ(F)G^\sigma(F) respectively. In this article, we study the compatibility between these two maps in the local base change setting. Further, an application of this compatibility is given in the context of linkage--which is the representation theoretic version of Brauer homomorphism.

Keywords

Cite

@article{arxiv.2305.00785,
  title  = {Compatibility of Kazhdan and Brauer homomorphism},
  author = {Sabyasachi Dhar},
  journal= {arXiv preprint arXiv:2305.00785},
  year   = {2025}
}

Comments

14 pages, final version. To appear in Canadian Math. Bulletin