English

The Derived $l$-Modular Unipotent Block of $p$-adic $\mathrm{GL}_n$

Representation Theory 2025-09-17 v1 Number Theory

Abstract

For a non-Archimedean local field FF of residue cardinality q=prq=p^r, we give an explicit classical generator VV for the bounded derived category Dfgb(H1(G))D_{fg}^b(\mathsf{H}_1(G)) of finitely generated unipotent representations of G=GLn(F)G=\mathrm{GL}_n(F) over an algebraically closed field of characteristic lpl\neq p. The generator VV has an explicit description that is much simpler than any known progenerator in the underived setting. This generalises a previous result of the author in the case where n=2n=2 and ll is odd dividing q+1q+1, and provides a triangulated equivalence between Dfgb(H1(G))D_{fg}^b(\mathsf{H}_1(G)) and the category of perfect complexes over the dg algebra of dg endomorphisms of a projective resolution of VV. This dg algebra can be thought of as a dg-enhanced Schur algebra. As an intermediate step, we also prove the analogous result for the case where FF is a finite field.

Keywords

Cite

@article{arxiv.2509.13088,
  title  = {The Derived $l$-Modular Unipotent Block of $p$-adic $\mathrm{GL}_n$},
  author = {Rose Berry},
  journal= {arXiv preprint arXiv:2509.13088},
  year   = {2025}
}