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Main Authors: Ghosh, Arkadev, Kannan, S. S.
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2604.25645
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author Ghosh, Arkadev
Kannan, S. S.
author_facet Ghosh, Arkadev
Kannan, S. S.
contents Let $G=PSL(n,\mathbb{C})$. Let $T$ be a maximal torus of $G$. Let $ω_{r}$ denote the $r^{th}$ fundamental weight. Let $\mathcal{L}(nω_{r})$ denote the line bundle on the Grassmannian $G_{r,n}$ associated to the character $nω_{r}$ of $T$. In an earlier work of Kannan and Sardar, it is proved that there is a unique minimal dimensional Schubert variety $X(w_{r,n})$ in $G_{r,n}$ admitting semistable points for the $T$-linearized ample line bundle $\mathcal{L}(nω_{r})$. Assume that $n=rq+1$, where $r,q\in\mathbb{N}$ and $q\geq 2$. In this paper, we study the GIT quotient of $X(w_{r,n})$ modulo a subtorus $T_{J_{r}}$ of $T$ generated by the one parameter subgroups of $T$ corresponding to the peaks of $w_{r,n}$. We prove that the GIT quotient of $X(w_{r,n})$ modulo $T_{J_{r}}$ is isomorphic to the total space of the $r^{th}$ stage of an iterated projective space bundle over $\mathbb{P}^{q-1}$.
format Preprint
id arxiv_https___arxiv_org_abs_2604_25645
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle GIT quotient of minimal dimensional Schubert variety modulo a subtorus
Ghosh, Arkadev
Kannan, S. S.
Algebraic Geometry
14M15, 14L35, 14F25
Let $G=PSL(n,\mathbb{C})$. Let $T$ be a maximal torus of $G$. Let $ω_{r}$ denote the $r^{th}$ fundamental weight. Let $\mathcal{L}(nω_{r})$ denote the line bundle on the Grassmannian $G_{r,n}$ associated to the character $nω_{r}$ of $T$. In an earlier work of Kannan and Sardar, it is proved that there is a unique minimal dimensional Schubert variety $X(w_{r,n})$ in $G_{r,n}$ admitting semistable points for the $T$-linearized ample line bundle $\mathcal{L}(nω_{r})$. Assume that $n=rq+1$, where $r,q\in\mathbb{N}$ and $q\geq 2$. In this paper, we study the GIT quotient of $X(w_{r,n})$ modulo a subtorus $T_{J_{r}}$ of $T$ generated by the one parameter subgroups of $T$ corresponding to the peaks of $w_{r,n}$. We prove that the GIT quotient of $X(w_{r,n})$ modulo $T_{J_{r}}$ is isomorphic to the total space of the $r^{th}$ stage of an iterated projective space bundle over $\mathbb{P}^{q-1}$.
title GIT quotient of minimal dimensional Schubert variety modulo a subtorus
topic Algebraic Geometry
14M15, 14L35, 14F25
url https://arxiv.org/abs/2604.25645