English

Chern character for twisted K-theory of orbifolds

K-Theory and Homology 2007-05-23 v2 Mathematical Physics Differential Geometry math.MP Operator Algebras

Abstract

For an orbifold X and αH3(X,Z)\alpha \in H^3(X, Z), we introduce the twisted cohomology Hc(X,α)H^*_c(X, \alpha) and prove that the Connes-Chern character establishes an isomorphism between the twisted K-groups Kα(X)CK_\alpha^* (X) \otimes C and twisted cohomology Hc(X,α)H^*_c(X, \alpha). This theorem, on the one hand, generalizes a classical result of Baum-Connes, Brylinski-Nistor, and others, that if X is an orbifold then the Chern character establishes an isomorphism between the K-groups of X tensored with C, and the compactly-supported cohomology of the inertia orbifold. On the other hand, it also generalizes a recent result of Adem-Ruan regarding the Chern character isomorphism of twisted orbifold K-theory when the orbifold is a global quotient by a finite group and the twist is a special torsion class, as well as Mathai-Stevenson's theorem regarding the Chern character isomorphism of twisted K-theory of a compact manifold.

Keywords

Cite

@article{arxiv.math/0505267,
  title  = {Chern character for twisted K-theory of orbifolds},
  author = {Jean-Louis Tu and Ping Xu},
  journal= {arXiv preprint arXiv:math/0505267},
  year   = {2007}
}

Comments

26 pages. To appear in Advances in Mathematics