We present a categorical point of view on dynamical quantum groups in terms of categories of Harish-Chandra bimodules. We prove Tannaka duality theorems for forgetful functors into the monoidal category of Harish-Chandra bimodules in terms of a slight modification of the notion of a bialgebroid. Moreover, we show that the standard dynamical quantum groups F(G) and F_q(G) are related to parabolic restriction functors for classical and quantum Harish-Chandra bimodules. Finally, we exhibit a natural Weyl symmetry of the parabolic restriction functor using Zhelobenko operators and show that it gives rise to the action of the dynamical Weyl group.
In addition to the previous paper, we present classical versions of the dynamical constructions in terms of shifted Poisson structures. Also, we begin a study of the Whittaker analog of the parabolic restriction functor that resulted in the next paper later.
We construct an element, which we call the Kirillov projector, that connects the topics of the title: on the one hand, it is defined using the Yangian of gl_N, on the other hand, it gives a canonical projection onto the space of Whittaker vectors for any Whittaker module over the mirabolic subalgebra. Using the Kirillov projector, we deduce some categorical properties of Whittaker modules, for instance, we prove a mirabolic analog of Skryabin's theorem. We also show that it quantizes a rational version of the Cremmer-Gervais r-matrix. As application, we construct a universal vertex-IRF transformation from the standard dynamical R-matrix to this constant one in categorical terms.
In this paper, we study intertwining operators between subregular Whittaker modules of $\gl_N$ generalizing, on the one hand, the classical exchange construction of dynamical quantum groups, on the other hand, earlier results for principal W-algebras. We explicitly construct them using the generators of W-algebras introduced by Brundan-Kleshchev. We interpret the fusion on intertwining operators in terms of categorical actions and compute the semi-classical limit of the corresponding monoidal isomorphisms which turn out to depend on dynamical-like parameters.
Typesetting lecture notes by Hiro Lee Tanaka at Summer School: Geometric Representation Theory and Low-dimensional Topology, Edinburgh 2019