Abstract

Braverman-Finkelberg arXiv:0711.2083 recently propose the geometric Satake correspondence for the affine Kac-Moody group \$G\_\textbackslashaff\$. They conjecture that intersection cohomology sheaves on the Uhlenbeck compactification of the framed moduli space of \$G\_\textbackslashmathrmcpt\$-instantons on \$\textbackslashRˆ4/\textbackslashZ\_r\$ correspond to weight spaces of representations of the Langlands dual group \$G\_\textbackslashaffˆ\textbackslashvee\$ at level \$r\$. When \$G = \textbackslashSL(l)\$, the Uhlenbeck compactification is the quiver variety of type \$\textbackslashalgsl(r)\_\textbackslashaff\$, and their conjecture follows from the author's earlier result and I.Frenkel's level-rank duality. They further introduce a convolution diagram which conjecturally gives the tensor product multiplicity (paper in preparation). In this paper, we develop the theory for the branching in quiver varieties and check this conjecture for \$G=\textbackslashSL(l)\$.

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