Turaev bicategories, generalized Yetter-Drinfel`d modules in 2-categories and a Turaev 2-category for bimonads in 2-categories

TL;DR

This paper introduces Turaev bicategories and pseudofunctors, generalizing classical structures to 2-categories, and constructs a Turaev 2-category for bimonads, extending the theory of Yetter-Drinfel'd modules and their applications in cyclic cohomology.

Contribution

It develops the theory of Turaev bicategories and pseudofunctors in 2-categories, introducing generalized Yetter-Drinfel'd modules and constructing a Turaev 2-category for bimonads, extending existing categorical frameworks.

Findings

Generalization of Turaev categories to bicategories and pseudofunctors.

Construction of a Turaev 2-category for bimonads in 2-categories.

Extension of results on pairs in involution to the 2-categorical setting.

Abstract

We introduce Turaev bicategories and Turaev pseudofunctors. On the one hand, they generalize the notions of Turaev categories (and Turaev functors), introduced at the turn of the millennium and originally called "crossed group categories" by Turaev himself, and the notions of bicategories and pseudofunctors, on the other. For bimonads in 2-categories, which we defined in one of our previous papers, we introduce generalized Yetter-Drinfel`d modules in 2-categories. These generalize to the 2-categorical setting the generalized Yetter-Drinfel`d modules (over a field) of Panaite and Staic, and thus also in particular the anti Yetter-Drinfel`d modules, introduced by Hajac-Khalkhali-Rangipour-Sommerhauser as coefficients for the cyclic cohomology of Hopf algebras, defined by Connes and Moscovici. We construct Turaev 2-category for bimonads in 2-categories as a Turaev extension of the 2-category of bimonads. This Turaev 2-category generalizes the Turaev category of generalized Yetter-Drinfel`d modules of Panaite and Staic. We also prove in the 2-categorical setting their results on pairs in involution, which in turn go back to modular pairs in involution of Connes and Moscovici.