Spherical varieties and Langlands duality
arXiv:math/0611323
Abstract
Let G be a connected reductive complex algebraic group. This paper is devoted to the space Z of meromorphic quasimaps from a curve into an affine spherical G-variety X. The space Z may be thought of as an algebraic model for the loop space of X. In this paper, we associate to X a connected reductive complex algebraic subgroup of the dual group . The construction of is via Tannakian formalism: we identify a certain tensor category Q(Z) of perverse sheaves on Z with the category of finite-dimensional representations of . Combinatorial shadows of the group govern many aspects of the geometry of X such as its compactifications and invariant differential operators. When X is a symmetric variety, the group coincides with that associated to the corresponding real form of G via the (real) geometric Satake correspondence.