The companion section for classical groups

Abstract

We use the companion matrix construction for ${\mathrm{GL}}_n$ to build canonical sections of the Chevalley map $[\mathfrak{g}/G]\to \mathfrak{g}//G$ for classical groups $G$ as well as the group $G_2$. To do so, we construct canonical tensors on the associated spectral covers. As an application, we make explicit lattice descriptions of affine Springer fibers and Hitchin fibers for classical groups and $G_2$.

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