  A relativistic description of spin 3/2 resonances and their decay channels is
presented by calculating their selfenergies and spectral functions. The full
vector-spinor structure is taken into account. Special emphasis is put on the
N*(1520) and its decay channels pi N, rho N and pi \Delta. All interactions are
formulated such that only the correct number of degrees of freedom of a spin
3/2 state is propagated. The obtained results are compared with several
approximations frequently used to avoid the complicated vector-spinor
structure. Since this structure is taken fully into account here, the quality
of the approximations can be judged.
