The dual group for a twisted Satake equivalence, and quadratic forms from gerbesAlgebra & Discrete Mathematics
|Speaker:||Ryan Reich, UCLA|
|Start time:||Thu, Feb 16 2012, 3:10PM|
I will describe a certain purely algebraic way of modifying the root data of a reductive group using a multiplicative quadratic form on its coweight lattice. Such quadratic forms can be geometrized as gerbes (the "higher" version of principal bundles) on the factorizable affine grassmannian, a collection of spaces appearing in the geometric Langlands program. I will also describe this correspondence and indicate how it can be invented by trying to prove the geometric Satake equivalence without knowing what that is.