Five-particle one-loop closed string amplitudes and supersymmetry relations

The explicit covariant forms for the three-boson-two-fermion and the one-boson-four-fermion scattering amplitudes at one-loop level in closed superstring theory are presented. The amplitudes are shown to have the correct factorization properties at kinematic poles, yielding as residues of these poles the well-known four-particle amplitudes. The analysis shows, for the first time at the one-loop level, a verification of the supersymmetry properties of the vertices. (orig.)