English

Rationality of extended unipotent characters

Representation Theory 2024-02-16 v1 Group Theory

Abstract

We determine the rationality properties of unipotent characters of finite reductive groups arising as fixed points of disconnected reductive groups under a Frobenius map. In the proof we use realisations of characters in \ell-adic cohomology groups of Deligne--Lusztig varieties as well as block theoretic considerations.

Keywords

Cite

@article{arxiv.2402.09960,
  title  = {Rationality of extended unipotent characters},
  author = {Olivier Dudas and Gunter Malle},
  journal= {arXiv preprint arXiv:2402.09960},
  year   = {2024}
}