Integral bases for TQFT modules and unimodular representations of mapping class groups

Non semi-simple TQFTs, Reidemeister torsion and Kashaev's invariants

We construct and study a new family of TQFTs based on nilpotent highest weight representations of quantum sl(2) at a root of unity indexed by generic complex numbers. This extends to cobordisms the non-semi-simple invariants defined in (arXiv:1202.3553) including the Kashaev invariant of links. Here the modular category framework does not apply and we use the ``universal construction''. Our TQFT provides a monoidal functor from a category of surfaces and their cobordisms into the category of graded finite dimensional vector spaces and their degree 0-morphisms and depends on the choice of a roo…

Maslov index, Lagrangians, Mapping Class Groups and TQFT

Given a mapping class f of an oriented surface Sigma and a lagrangian lambda in the first homology of Sigma, we define an integer n_{lambda}(f). We use n_{lambda}(f) (mod 4) to describe a universal central extension of the mapping class group of Sigma as an index-four subgroup of the extension constructed from the Maslov index of triples of lagrangian subspaces in the homology of the surface. We give two descriptions of this subgroup. One is topological using surgery, the other is homological and builds on work of Turaev and work of Walker. Some applications to TQFT are discussed. They are bas…

On modular group representations associated to SO$(p)_2$-TQFTs

In this paper, we prove that for any odd prime larger than 3, the modular group representation associated to the SO$(p)_2$-TQFT can be defined over the ring of integers of a cyclotomic field. We will provide explicit integral bases. In the last section, we will relate these representations to the Weil representations over finite fields.

Alterfold 拓扑量子场论

Alterfold Topological Quantum Field Theory

本文提出 3-alterfold TQFT，刻画其基并统一解释 Levin-Wen、RT 与 TV 模型，证明酉性、Morita 等价性及高亏格拓扑指标的映射类群等变性。

Categorification: tangle invariants and TQFTs

Based on different views on the Jones polynomial we review representation theoretic categorified link and tangle invariants. We unify them in a common combinatorial framework and connect them via the theory of Soergel bimodules. The influence of these categorifications on the development of 2-representation theory and the interaction between topological invariants and 2-categorical structures is discussed. Finally, we indicate how categorified representations of quantum groups on the one hand and monoidal 2-categories of Soergel bimodules on the other hand might lead to new interesting 4-dimen…

$a\times b=c$ in $2+1$D TQFT

We study the implications of the anyon fusion equation $a\times b=c$ on global properties of $2+1$D topological quantum field theories (TQFTs). Here $a$ and $b$ are anyons that fuse together to give a unique anyon, $c$. As is well known, when at least one of $a$ and $b$ is abelian, such equations describe aspects of the one-form symmetry of the theory. When $a$ and $b$ are non-abelian, the most obvious way such fusions arise is when a TQFT can be resolved into a product of TQFTs with trivial mutual braiding, and $a$ and $b$ lie in separate factors. More generally, we argue that the appearance …

Domain walls between 3d phases of Reshetikhin-Turaev TQFTs

We study surface defects in three-dimensional topological quantum field theories which separate different theories of Reshetikhin-Turaev type. Based on the new notion of a Frobenius algebra over two commutative Frobenius algebras, we present an explicit and computable construction of such defects. It specialises to the construction in Carqueville et al., arXiv:1710.10214 if all 3-strata are labelled by the same topological field theory. We compare the results to the model-independent analysis in Fuchs et al., arXiv:1203.4568 and find agreement.

A QFT for non-semisimple TQFT

We construct a family of 3d quantum field theories $\mathcal T_{n,k}^A$ that conjecturally provide a physical realization -- and derived generalization -- of non-semisimple mathematical TQFT's based on the modules for the quantum group $U_q(\mathfrak{sl}_n)$ at an even root of unity $q=\text{exp}(iπ/k)$. The theories $\mathcal T_{n,k}^A$ are defined as topological twists of certain 3d $\mathcal N=4$ Chern-Simons-matter theories, which also admit string/M-theory realizations. They may be thought of as $SU(n)_{k-n}$ Chern-Simons theories, coupled to a twisted $\mathcal N=4$ matter sector (the so…

Turaev-Viro TQFT二维有隙相之间畴壁的弱Hopf管代数

Weak Hopf tube algebra for domain walls between 2d gapped phases of Turaev-Viro TQFTs

本文通过构造畴壁管代数研究Turaev-Viro TQFT二维有隙相之间的畴壁，证明其具有C*弱Hopf代数结构，并建立其与边界管代数Drinfeld量子双的同构，从而用表示论统一刻画畴壁上的拓扑激发与缺陷。

Four dimensional topological quantum field theory, Hopf categories, and the canonical bases

We propose a new mwthod of constructing 4D-TQFTs. The method uses a new type of algebraic structure called a Hopf Category. We also outline the construction of a family of Hopf categories related to the quantum groups, using the canonical bases.

Homological Construction of Quantum Representations of Mapping Class Groups

We provide a homological model for a family of quantum representations of mapping class groups arising from non-semisimple TQFTs (Topological Quantum Field Theories). Our approach gives a new geometric point of view on these representations, and it gathers into one theory two of the most promising constructions for investigating linearity of mapping class groups. More precisely, if $\varSigma_{g,1}$ is a surface of genus $g$ with $1$ boundary component, we consider a (crossed) action of its mapping class group $\mathrm{Mod}(\varSigma_{g,1})$ on the homology of its configuration space $\mathrm{…

在$\mathrm{SO}(3)$模函子上构造霍奇结构

Construction of Hodge structures on the $\mathrm{SO}(3)$ modular functors

本文证明亏格0的SO(3)模函子具有几何起源，并基于同调模型构造其上的整值霍奇结构变体，同时用Künneth公式几何地恢复粘合性质。

量子SL+(N,R)作为局部紧量子群

Quantum $SL^+(N,\mathbb{R})$ as a locally compact quantum group

本文通过Drinfeld-Jimbo量化方法，构造了首个纯连续的q-变形李型局部紧量子群，基于完全正部分的单模变形参数。