Skip to main content
Article
Equivariant homology and K-theory of affine Grassmannians and Toda lattices
COMPOSITIO MATHEMATICA
  • R Bezrukavnikov
  • M Finkelberg
  • I Mirkovic, University of Massachusetts - Amherst
Publication Date
2005
Abstract

For an almost simple complex algebraic group G with affine Grassmannian $\text{Gr}_G=G(\mathbb{C}(({\rm t})))/G(\mathbb{C}[[{\rm t}]])$, we consider the equivariant homology $H^{G(\mathbb{C}[[{\rm t}]])}(\text{Gr}_G)$ and K-theory $K^{G(\mathbb{C}[[{\rm t}]])}(\text{Gr}_G)$. They both have a commutative ring structure with respect to convolution. We identify the spectrum of homology ring with the universal group-algebra centralizer of the Langlands dual group $\check G$, and we relate the spectrum of K-homology ring to the universal group-group centralizer of G and of $\check G$. If we add the loop-rotation equivariance, we obtain a noncommutative deformation of the (K-)homology ring, and thus a Poisson structure on its spectrum. We relate this structure to the standard one on the universal centralizer. The commutative subring of $G(\mathbb{C}[[{\rm t}]])$-equivariant homology of the point gives rise to a polarization which is related to Kostant's Toda lattice integrable system. We also compute the equivariant K-ring of the affine Grassmannian Steinberg variety. The equivariant K-homology of GrG is equipped with a canonical basis formed by the classes of simple equivariant perverse coherent sheaves. Their convolution is again perverse and is related to the Feigin–Loktev fusion product of $G(\mathbb{C}[[{\rm t}]])$-modules.

Comments

This is the pre-published version harvested from arXiv. The published version is located at http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=297084

Pages
746-768
Citation Information
R Bezrukavnikov, M Finkelberg and I Mirkovic. "Equivariant homology and K-theory of affine Grassmannians and Toda lattices" COMPOSITIO MATHEMATICA Vol. 141 Iss. 3 (2005)
Available at: http://works.bepress.com/ivan_mirkovic/17/