Geometric Satake equivalence in mixed characteristic and Springer correspondence

Abstract

The geometric Satake equivalence and the Springer correspondence are closely related when restricting to small representations of the Langlands dual group. We prove this result for étale sheaves, including the case of the mixed characteristic affine Grassmannian, assuming a sufficient ramification. In this process, we construct a monoidal structure on the restriction functor of Satake categories. We construct also a canonical isomorphism between a mixed characteristic affine Grassmannian under a sufficient ramification and an equal characteristic one.

37 pages, changed the proof of Theorem 1.1(4.12) and the assumption on p and the proof of Theorem 1.2