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A generalization of Springer theory using nearby cycles

Mikhail Grinberg
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Abstract

Let g be a complex semisimple Lie algebra, and f : g --> g/G the adjoint quotient map. Springer theory of Weyl group representations can be seen as the study of the singularities of f. We give a generalization of Springer theory to visible, polar representations. It is a class of rational representations of complex reductive groups, for which the invariant theory works by analogy with the adjoint representations. Let G|V be such a representation, f : V --> V/G the quotient map, and P the sheaf of nearby cycles of f. We show that the Fourier transform of P is an intersection homology sheaf on V*. Associated to G|V, there is a finite complex reflection group W, called the Weyl group of G|V. We describe the endomorphism ring of P as a deformation of the group algebra of W.

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Mikhail Grinberg. 1998-06-02. A generalization of Springer theory using nearby cycles. https://arxiv.org/abs/math/9802042

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