N=4 Maxwell-Einstein supergravity in five dimensions and its SU(2) gauging

We construct the Usp(4) invariant action of an arbitrary number, n, of N=4 abelian vector supermultiplets in d=5 coupled to d=5, N=4 supergravity. The scalar fields of the vector supermultiplets parametrize the coset space SO(5,n)/[SO(5) x SO(n)]. We further show that an SU(2) subgroup of Usp(4) can be gauged if n>=1 but that in this case there is no maximally symmetric d=5 ground state. If n=0 the SU(2) gauging is not possible, because the n=1 gauged Maxwell/Einstein supermultiplet is irreducible. (orig.)