Curvature formulas of holomorphic curves on $C^*$-algebras and Cowen-Douglas Operators

Abstract

For $\Omega\subseteq \mathbb{C}$ a connected open set, and ${\mathcal U}$ a unital $C^*$-algebra, let ${\mathcal I} ({\mathcal U})$ and ${\mathcal P}({\mathcal U})$ denote the sets of all idempotents and projections in ${\mathcal U}$ respectively. ${\mathcal P}({\mathcal U})$ is called as the Grassmann manifold of $\mathcal U$ and ${\mathcal I} ({\mathcal U})$ is called as the extended Grassmann manifold. If $P:\Omega \rightarrow {\mathcal P}({\mathcal U})$ is a real-analytic ${\mathcal U}$-valued map which satisfies $\overline{\partial} PP=0$, then $P$ is called a holomorphic curve on ${\mathcal P}({\mathcal U})$. In this note, we will define the formulaes of curvature and it's covariant derivatives for holomorphic curves on $C^*$-algebras. It can be regarded as the generalization of curvature and it's covariant derivatives of the classical holomorphic curves. By using the curvature formulae, we give the unitarily and similarity classifications for the holomorphic curves and extended holomorphic curves on $C^*$-algebras respectively. And we also give a description of the trace of the covariant derivatives of curvature for any Hermitian holomorphic vector bundles. As applications, we also discuss the relationship between holomorphic curves, extended holomorphic curves, similarity of holomorphic Hermitian vector bundles and similarity of Cowen-Douglas operators.