English

Deformations of $G$-valued pseudocharacters

Number Theory 2026-04-01 v2 Representation Theory

Abstract

We define a deformation space of V. Lafforgue's GG-valued pseudocharacters of a profinite group Γ\Gamma for a possibly disconnected reductive group GG. We show, that this definition generalizes Chenevier's construction. We show that the universal pseudodeformation ring is noetherian and that the functor of continuous GG-pseudocharacters on affinoid Qp\mathbb{Q}_p-algebras is represented by a quasi-Stein rigid analytic space, whenever Γ\Gamma is topologically finitely generated. We also show that the pseudodeformation ring is noetherian, when Γ\Gamma satisfies Mazur's condition Φp\Phi_p and GG satisfies a certain invariant-theoretic condition. For G=Sp2nG = \mathrm{Sp}_{2n} we describe three types of obstructed loci in the special fiber of the universal pseudodeformation space of an arbitrary residual pseudocharacter and give upper bounds for their dimension.

Keywords

Cite

@article{arxiv.2310.14886,
  title  = {Deformations of $G$-valued pseudocharacters},
  author = {Julian Quast},
  journal= {arXiv preprint arXiv:2310.14886},
  year   = {2026}
}

Comments

52 pages, minor changes, numbering agrees with published version

R2 v1 2026-06-28T12:58:53.826Z