English

Type $II$ quantum subgroups of $\mathfrak{sl}_N$. $I$: Symmetries of local modules

Quantum Algebra 2022-10-28 v4 Category Theory Operator Algebras Representation Theory

Abstract

This paper is the first of a pair that aims to classify a large number of the type IIII quantum subgroups of the categories C(slr+1,k)\mathcal{C}(\mathfrak{sl}_{r+1},k). In this work we classify the braided auto-equivalences of the categories of local modules for all known type II quantum subgroups of C(slr+1,k)\mathcal{C}(\mathfrak{sl}_{r+1},k). We find that the symmetries are all non-exceptional except for four cases (up to level-rank duality). These exceptional cases are the orbifolds C(sl2,16)Rep(Z2)\mathcal{C}( \mathfrak{sl}_{2},16)_{\operatorname{Rep}(\mathbb{Z}_2)}, C(sl3,9)Rep(Z3)\mathcal{C}( \mathfrak{sl}_{3},9)_{\operatorname{Rep}(\mathbb{Z}_3)}, C(sl4,8)Rep(Z4)\mathcal{C}( \mathfrak{sl}_{4},8)_{\operatorname{Rep}(\mathbb{Z}_4)}, and C(sl5,5)Rep(Z5)\mathcal{C}( \mathfrak{sl}_{5},5)_{\operatorname{Rep}(\mathbb{Z}_5)}. We develop several technical tools in this work. We give a skein theoretic description of the orbifold quantum subgroups of C(slr+1,k)\mathcal{C}(\mathfrak{sl}_{r+1},k). Our methods here are general, and the techniques developed will generalise to give skein theory for any orbifold of a braided tensor category. We also give a formulation of orthogonal level-rank duality in the type DD-DD case, which is used to construct one of the exceptionals. Finally we uncover an unexpected connection between quadratic categories and exceptional braided auto-equivalences of the orbifolds. We use this connection to construct two of the four exceptionals. In the sequel to this paper we will use the classified braided auto-equivalences to construct the corresponding type IIII quantum subgroups of the categories C(slr+1,k)\mathcal{C}(\mathfrak{sl}_{r+1},k). When paired with Gannon's type II classification for r6r\leq 6, this will complete the type IIII classification for these same ranks. This paper includes an appendix by Terry Gannon, which provides useful results on the dimensions of objects in the categories C(slr+1,k)\mathcal{C}(\mathfrak{sl}_{r+1},k).

Keywords

Cite

@article{arxiv.2102.09065,
  title  = {Type $II$ quantum subgroups of $\mathfrak{sl}_N$. $I$: Symmetries of local modules},
  author = {Cain Edie-Michell and with an appendix by Terry Gannon},
  journal= {arXiv preprint arXiv:2102.09065},
  year   = {2022}
}

Comments

46 pages, appendix added by Terry Gannon which simplifies some arguments, significant changes made based off referee reports