Super-Poincaré invariant Koba-Nielsen formulas for the superstring

The new spacetime-supersymmetric description of the superstring is used to compute tree-level scattering amplitudes for an arbitrary number of massless four-dimensional states. The resulting Koba-Nielsen formula is manifestly SO(3,1) super-Poincaré invariant and is easily generalized to scattering in the presence of a D-brane.