Singular fibers of the Gelfand--Cetlin system on $\mathfrak{u}(n{)}^{\ast }$

Damien Bouloc, Eva Miranda, Nguyen Tien Zung

In this paper, we show that every singular fiber of the Gelfand--Cetlin system on coadjoint orbits of unitary groups is a smooth isotropic submanifold which is diffeomorphic to a $…