English

A categorical Connes' $\chi(M)$

Operator Algebras 2021-11-12 v1 Category Theory Quantum Algebra

Abstract

Popa introduced the tensor category χ~(M)\tilde{\chi}(M) of approximately inner, centrally trivial bimodules of a II1\rm{II}_{1} factor MM, generalizing Connes' χ(M)\chi(M). We extend Popa's notions to define the W\rm W^*-tensor category Endloc(C)\operatorname{End}_{\rm loc}(\mathcal{C}) of local endofunctors on a W\rm W^*-category C\mathcal{C}. We construct a unitary braiding on Endloc(C)\operatorname{End}_{\rm loc}(\mathcal{C}), giving a new construction of a braided tensor category associated to an arbitrary W\rm W^*-category. For the W\rm W^*-category of finite modules over a II1\rm{II}_{1} factor, this yields a unitary braiding on Popa's χ~(M)\tilde{\chi}(M), which extends Jones' κ\kappa invariant for χ(M)\chi(M). Given a finite depth inclusion M0M1M_{0}\subseteq M_{1} of non-Gamma II1\rm{II}_1 factors, we show that the braided unitary tensor category χ~(M)\tilde{\chi}(M_{\infty}) is equivalent to the Drinfeld center of the standard invariant, where MM_{\infty} is the inductive limit of the associated Jones tower. This implies that for any pair of finite depth non-Gamma subfactors N0N1N_{0}\subseteq N_{1} and M0M1M_{0}\subseteq M_{1}, if the standard invariants are not Morita equivalent, then the inductive limit factors NN_{\infty} and MM_{\infty} are not stably isomorphic.

Keywords

Cite

@article{arxiv.2111.06378,
  title  = {A categorical Connes' $\chi(M)$},
  author = {Quan Chen and Corey Jones and David Penneys},
  journal= {arXiv preprint arXiv:2111.06378},
  year   = {2021}
}

Comments

52 pages, many tikz figures

R2 v1 2026-06-24T07:35:29.097Z