Turaev bicategories, generalized Yetter-Drinfel`d modules in 2-categories and a Turaev 2-category for bimonads in 2-categories (1807.02893v1)

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-Drinfeld modules in 2-categories. These generalize to the 2-categorical setting the generalized Yetter-Drinfeld modules (over a field) of Panaite and Staic, and thus also in particular the anti Yetter-Drinfeld 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-Drinfeld 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.