#### Volume 18, issue 7 (2018)

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Logarithmic Hennings invariants for restricted quantum ${\mathfrak{sl}}(2)$

### Anna Beliakova, Christian Blanchet and Nathan Geer

Algebraic & Geometric Topology 18 (2018) 4329–4358
##### Abstract

We construct a Hennings-type logarithmic invariant for restricted quantum $\mathfrak{s}\mathfrak{l}\left(2\right)$ at a  root of unity. This quantum group $U$ is not quasitriangular and hence not ribbon, but factorizable. The invariant is defined for a pair: a $3$–manifold $M$ and a colored link $L$ inside $M$. The link $L$ is split into two parts colored by central elements and by trace classes, or elements in the Hochschild homology of $U$, respectively. The two main ingredients of our construction are the universal invariant of a string link with values in tensor powers of $U$, and the modified trace introduced by the third author with his collaborators and computed on tensor powers of the regular representation. Our invariant is a colored extension of the logarithmic invariant constructed by Jun Murakami.

##### Keywords
quantum invariants, links, Hopf algebras, quantum Groups
##### Mathematical Subject Classification 2010
Primary: 57M27
Secondary: 17B37, 57M25
##### Publication
Received: 10 April 2018
Accepted: 7 June 2018
Published: 11 December 2018
##### Authors
 Anna Beliakova Institut für Mathematik Universität Zürich Zurich Switzerland Christian Blanchet Institut de Mathématiques de Jussieu - Paris Rive Gauche Université Paris 7 (Denis Diderot) Paris France Nathan Geer Department of Mathematics and Statistics Utah State University Logan, UT United States