Five-dimensional supergravity in N=1 superspace

We give a formulation of linearized minimal five-dimensional supergravity in N=1 superspace. Infinitesimal local 5D diffeomorphisms, local 5D Lorentz transformations, and local 5D supersymmetry are all realized as off-shell superfield transformations. Compactification on an S-1/Z(2) orbifold and couplings to brane-localized supermultiplets are very simple in this formalism. We use this to show that five-dimensional supergravity can naturally generate mu and Bmu terms of the correct size in gaugino- or radion-mediated supersymmetry breaking. We also include a self-contained review of linearized minimal 4D supergravity in superspace.