Paper detail

Fusion and braiding in finite and affine Temperley-Lieb categories

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 infinite `arc' 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.