English

GIT quotient of minimal dimensional Schubert variety modulo a subtorus

Algebraic Geometry 2026-04-29 v1

Abstract

Let G=PSL(n,C)G=PSL(n,\mathbb{C}). Let TT be a maximal torus of GG. Let ωr\omega_{r} denote the rthr^{th} fundamental weight. Let L(nωr)\mathcal{L}(n\omega_{r}) denote the line bundle on the Grassmannian Gr,nG_{r,n} associated to the character nωrn\omega_{r} of TT. In an earlier work of Kannan and Sardar, it is proved that there is a unique minimal dimensional Schubert variety X(wr,n)X(w_{r,n}) in Gr,nG_{r,n} admitting semistable points for the TT-linearized ample line bundle L(nωr)\mathcal{L}(n\omega_{r}). Assume that n=rq+1n=rq+1, where r,qNr,q\in\mathbb{N} and q2q\geq 2. In this paper, we study the GIT quotient of X(wr,n)X(w_{r,n}) modulo a subtorus TJrT_{J_{r}} of TT generated by the one parameter subgroups of TT corresponding to the peaks of wr,nw_{r,n}. We prove that the GIT quotient of X(wr,n)X(w_{r,n}) modulo TJrT_{J_{r}} is isomorphic to the total space of the rthr^{th} stage of an iterated projective space bundle over Pq1\mathbb{P}^{q-1}.

Keywords

Cite

@article{arxiv.2604.25645,
  title  = {GIT quotient of minimal dimensional Schubert variety modulo a subtorus},
  author = {Arkadev Ghosh and S. S. Kannan},
  journal= {arXiv preprint arXiv:2604.25645},
  year   = {2026}
}

Comments

31 Pages

R2 v1 2026-07-01T12:39:16.604Z