English

Twisted crossed products of Banach algebras

Functional Analysis 2026-05-19 v3 Dynamical Systems Operator Algebras

Abstract

Given a locally compact group GG, a nondegenerate Banach algebra AA with a contractive approximate identity, a twisted action (α,σ)(\alpha, \sigma) of GG on AA, and a family R\mathcal{R} of uniformly bounded representations of AA on Banach spaces, we define the twisted crossed product FR(G,A,α,σ)F_\mathcal{R}(G,A,\alpha, \sigma). When R\mathcal{R} consists of contractive representations, we show that FR(G,A,α,σ)F_\mathcal{R}(G,A,\alpha, \sigma) is a Banach algebra with a contractive approximate identity, which can also be characterized by an isometric universal property. As an application, we specialize to the LpL^p-operator algebra setting, defining both the LpL^p-twisted crossed product and the reduced version. Finally, we give a generalization of the so-called Packer-Raeburn trick to the LpL^p-setting, showing that any LpL^p-twisted crossed product is "stably" isometrically isomorphic to an untwisted one.

Keywords

Cite

@article{arxiv.2509.24106,
  title  = {Twisted crossed products of Banach algebras},
  author = {Alonso Delfín and Carla Farsi and Judith Packer},
  journal= {arXiv preprint arXiv:2509.24106},
  year   = {2026}
}

Comments

AMSLaTeX; 30 pages (v3: Final version accepted to the Journal of Mathematical Analysis and Applications)