Decay of Excited D-branes

We calculate the leading order interactions of massless D-brane excitations. Their 4-point functions are found to be identical to those found in type I theory. The amplitude for two massless D-brane fluctuations to produce a massless closed string is found to possess interesting new structure. As a function of its single kinematic invariant, it displays an infinite sequence of alternating zeros and poles. At high transverse momenta, this amplitude decays exponentially, indicating a growing effective thickness of the D-brane. This amplitude is the leading process by which non-extremal D-branes produce Hawking radiation.