Factorization of holomorphic matrices and Kazhdan's property (T)

Abstract

In this article we deduce some algebraic properties for the group Sp2n(O(X)) of holomorphic symplectic matrices on a Stein space X: holomorphic factorization, exponential factorization, and Kazhdan's property (T). In holomorphic factorization we combine a recent result of the third author and K-theory tools to give explicit bounds for the case when X is one-dimensional or two-dimensional. Next we use them to find bounds for exponential factorization. As a further application, we show that the elementary symplectic group Ep2n(O(X)) admits Kazhdan's property (T).