Greybody Factors for Black Holes in Four Dimensions: Particles with Spin

We compute the emission spectrum of minimally coupled particles with spin that are Hawking radiated from four dimensional black holes in string theory. For a range of the black hole parameters the result has a product structure that may be interpreted in terms of the respective right- and left-moving thermal correlation functions of an effective string model. For spin-one and spin-two particles a novel cancellation between contributions to the wave function is needed to ensure this outcome. The form of the spectra suggests that the four-dimensional effective string description is ``heterotic'': particles with spin are emitted from the right-moving sector, only.