Integrable Crystals and Restriction to Levi Subgroups Via Generalized Slices in the Affine Grassmannian

Functional Analysis and Its Applications. 2018. Vol. 52. No. 2. P. 113–133.

Krylov V.

Let $G$ be a connected reductive algebraic group over $\mathbb{C}$. Let $\Lambda^{+}_{G}$ be the monoid of dominant weights of $G$. We construct the integrable crystals $\mathbf{B}^{G}(\lambda),\ \lambda\in\Lambda^{+}_{G}$, using the geometry of generalized transversal slices in the affine Grassmannian of the Langlands dual group. We construct the tensor product maps $\mathbf{p}_{\lambda_{1},\lambda_{2}}\colon \mathbf{B}^{G}(\lambda_{1}) \otimes \mathbf{B}^{G}(\lambda_{2}) \rightarrow \mathbf{B}^{G}(\lambda_{1}+\lambda_{2})\cup\{0\}$ in terms of multiplication of generalized transversal slices. Let $L \subset G$ be a Levi subgroup of $G$. We describe the restriction to Levi $\operatorname{Res}^G_L\colon\operatorname{Rep}(G)\rightarrow\operatorname{Rep}(L)$ in terms of the hyperbolic localization functors for the generalized transversal slices.

Keywords: affine Grassmannian, аффинный грассманниан, Kashiwara crystals, geometric Satake isomorphism, generalized slices, кристаллы Кашивары, геометрическое соответствие Сатаке, обобщенные срезы

Publication based on the results of: Алгебраическая геометрия и ее приложения (2018)