Generating kernel for the boson realisation of symplectic algebras

Abstract
The discussion of boson realisations of symplectic algebras requires as an essential ingredient an operator K needed for the passage from the Dyson to the Holstein-Primakoff realisation. In previous papers the matrix form of K2 was derived through appropriate recursion relations. In the present analysis the authors show that K2 can be determined in explicit and closed form as the overlap of coherent states of the symplectic group. The matrix elements of K2 can then be obtained by expanding this overlap in terms of appropriate eigenstates.