Equivariant $\mathbb R$-test configurations of polarized spherical varieties

Abstract

Let $G$ be a connected, complex reductive Lie group and $G/H$ a spherical homogenous space. Let $(X,L)$ be a polarized $G$-variety which is a spherical embedding of $G/H$. In this paper we classify $G$-equivariant normal $\mathbb R$-test configurations of $(X,L)$ via combinatory data. In particular we classify the special ones, and prove a finiteness theorem of central fibres of $G$-equivariant special $\mathbb R$-test configurations. Also, as an application we study the semistable degeneration problem of a $\mathbb Q$-Fano spherical variety.