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Torus quotient of the Grassmannian $G_{n,2n}$

Authors :
Nayek, Arpita
Saha, Pinakinath
Source :
Comptes Rendus. Mathématique, Vol 361, Iss G9, Pp 1499-1509 (2023)
Publication Year :
2023
Publisher :
Académie des sciences, 2023.

Abstract

Let $G_{n,2n}$ be the Grassmannian parameterizing the $n$-dimensional subspaces of $\mathbb{C}^{2n}$. The Picard group of $G_{n,2n}$ is generated by a unique ample line bundle $\mathcal{O}(1)$. Let $T$ be a maximal torus of $\mathrm{SL}(2n,\mathbb{C})$ which acts on $G_{n,2n}$ and $\mathcal{O}(1)$. By [10, Theorem 3.10, p. 764], $2$ is the minimal integer $k$ such that $\mathcal{O}(k)$ descends to the GIT quotient. In this article, we prove that the GIT quotient of $G_{n,2n}$ ($n\ge 3$) by $T$ with respect to $\mathcal{O}(2)=\mathcal{O}(1)^{\otimes 2}$ is not projectively normal when polarized with the descent of $\mathcal{O}(2)$.

Details

Language :
English, French
ISSN :
17783569
Volume :
361
Issue :
G9
Database :
Directory of Open Access Journals
Journal :
Comptes Rendus. Mathématique
Publication Type :
Academic Journal
Accession number :
edsdoj.50f56942386e4d6a84241c81adc1092e
Document Type :
article
Full Text :
https://doi.org/10.5802/crmath.501