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arXiv · 2609.29537

A Cotangent Model for the Next-to-Minimal Orbit of E7

Boming Jia
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Abstract

Let $\mathcal O_{2A_1}$ be the next-to-minimal nilpotent orbit of the complex simple Lie algebra of type $E_7$. Let $\mathfrak p_7$ be the maximal parabolic subalgebra corresponding to the simple root $α_7$, and let $\mathfrak u^+$ be its nilpotent radical. We prove that the affinization $T^*(\mathcal O_{2A_1}\cap\mathfrak u^+)^{\mathrm{aff}}$ of the cotangent bundle of $\mathcal O_{2A_1}\cap\mathfrak u^+$ is isomorphic to the nilpotent orbit closure $\overline{\mathcal O}_{2A_1}$ as affine varieties.

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Boming Jia. 2026-08-27. A Cotangent Model for the Next-to-Minimal Orbit of E7. https://arxiv.org/abs/2609.29537

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