English

Intrinsic Chern-Connes Characters for Crossed Products by $\mathbb Z^d$

Operator Algebras 2015-01-20 v2 Strongly Correlated Electrons Mathematical Physics math.MP

Abstract

We present a natural imbedding of the crossed product AξZd\mathcal A \rtimes_\xi \mathbb Z^d into the CC^\ast-algebra of adjointable operators over the standard Hilbert A\mathcal A-module HA\mathcal H_{\mathcal A}. By replacing the representations on Hilbert spaces with this canonical imbedding, we define Fredholm modules and corresponding Chern-Connes characters that are intrinsic to the CC^\ast-dynamical system (A,ξ,Zd)(\mathcal A,\xi,\mathbb Z^d). The compression of the Dirac operator against projectors from AξZd\mathcal A \rtimes_\xi \mathbb Z^d produces generalized Fredholm operators over HA\mathcal H_{\mathcal A} and Mingo's index defines a KKKK-map from K0(AξZd)K_0(\mathcal A \rtimes_\xi \mathbb Z^d) to K(A)K(\mathcal A). Using a generalized Fedosov principle and a generalized Fedosov formula, we prove an index formula for the pairing of the intrinsic Chern-Connes characters and K0(AξZd)K_0(\mathcal A \rtimes_\xi \mathbb Z^d). This pairing takes values in the image of K0(A)K_0(\mathcal A) in R\mathbb R under a canonical trace. A local index formula enables new applications in condensed matter physics to the so called weak topological invariants.

Keywords

Cite

@article{arxiv.1501.03479,
  title  = {Intrinsic Chern-Connes Characters for Crossed Products by $\mathbb Z^d$},
  author = {Emil Prodan},
  journal= {arXiv preprint arXiv:1501.03479},
  year   = {2015}
}

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