English

The Cayley transform in complex, real and graded $K$-theory

K-Theory and Homology 2020-06-09 v2 Mathematical Physics math.MP Operator Algebras

Abstract

We use the Cayley transform to provide an explicit isomorphism at the level of cycles from van Daele KK-theory to KKKK-theory for graded CC^*-algebras with a real structure. Isomorphisms between KKKK-theory and complex or real KK-theory for ungraded CC^*-algebras are a special case of this map. In all cases our map is compatible with the computational techniques required in physical and geometrical applications, in particular index pairings and Kasparov products. We provide applications to real KK-theory and topological phases of matter.

Keywords

Cite

@article{arxiv.1912.07158,
  title  = {The Cayley transform in complex, real and graded $K$-theory},
  author = {Chris Bourne and Johannes Kellendonk and Adam Rennie},
  journal= {arXiv preprint arXiv:1912.07158},
  year   = {2020}
}

Comments

v2: 43 pages, minor revisions. To appear in Internat. J. Math

R2 v1 2026-06-23T12:46:37.154Z