Fusion and braiding in finite and affine Temperley-Lieb categories (1606.04530v1)

Abstract: Finite Temperley-Lieb (TL) algebras are diagram-algebra quotients of (the group algebra of) the famous Artin's braid group $B_N$, while the affine TL algebras arise as diagram algebras from a generalized version of the braid group. We study asymptotic $N\to\infty$' representation theory of these quotients (parametrized by $q\in\mathbb{C}^{\times}$) from a perspective of braided monoidal categories. Using certain idempotent subalgebras in the finite and affine algebras, we construct infinitearc' towers of the diagram algebras and the corresponding direct system of representation categories, with terms labeled by $N\in\mathbb{N}$. The corresponding direct-limit category is our main object of studies. For the case of the finite TL algebras, we prove that the direct-limit category is abelian and highest-weight at any $q$ and endowed with braided monoidal structure. The most interesting result is when $q$ is a root of unity where the representation theory is non-semisimple. The resulting braided monoidal categories we obtain at different roots of unity are new and interestingly they are not rigid. We observe then a fundamental relation of these categories to a certain representation category of the Virasoro algebra and give a conjecture on the existence of a braided monoidal equivalence between the categories. This should have powerful applications to the study of the `continuum' limit of critical statistical mechanics systems based on the TL algebra. We also introduce a novel class of embeddings for the affine Temperley-Lieb algebras and related new concept of fusion or bilinear $\mathbb{N}$-graded tensor product of modules for these algebras. We prove that the fusion rules are stable with the index $N$ of the tower and prove that the corresponding direct-limit category is endowed with an associative tensor product. We also study the braiding properties of this affine TL fusion.