Symmetric differentials and jets extension of $L^2$ holomorphic functions

Abstract

Let $\Sigma ={\mathbb{B}}^n/\Gamma$ be a complex hyperbolic space with discrete subgroup $\Gamma$ of the automorphism group of the unit ball ${\mathbb{B}}^n$ and $\Omega$ be a quotient of ${\mathbb{B}}^n\times {\mathbb{B}}^n$ under the diagonal action of $\Gamma$ which is a holomorphic ${\mathbb{B}}^n$-fiber bundle over $\Sigma$. The goal of this article is to investigate the relation between symmetric differentials of $\Sigma$ and the weighted $L^2$ holomorphic functions of $\Omega$. If there exists a holomorphic function on $\Omega$ and it vanishes up to $k$-th order on the maximal compact complex variety in $\Omega$, then there exists a symmetric differential of degree $k+1$ on $\Sigma$. Using this property, we show that $\Sigma$ always has a symmetric differential of degree $N$ for any $N\ge n+2$. Moreover if $\Sigma$ is compact, for each symmetric differential over $\Sigma$ we construct a weighted $L^2$ holomorphic function on $\Omega$. We also show that any bounded holomorphic function on $\Omega$ is constant when $H^0(\Sigma ,S^m{T}_{\Sigma }^{\ast })=0$ for every $0<m\le n+1$.