Zhengyu Mao, Stephen Rallis
Abstract We compute the spherical functions on the symmetric space Sp 2 n / Sp n × Sp n and derive a Plancherel formula for functions on the symmetric space. As an application of the Plancherel formula, we prove an identity which amounts to the fundamental lemma of a relative trace identity between Sp 2 n and $\widetilde {{\rm Sp}}_n$ .