The scattering of strings by a black hole

We study the elastic and inelastic scattering of strings by a Schwarzschild's black hole. Pair creation takes place (and in all the modes) as a consequence of the composite structure (oscillator modes) of the string. The S-matrix amplitudes including the pair-creation rate are found at first order in √α'/RS (√α' = Planck's length and RS = Schwarzschild's radius). Explicit computations are made in the weak-field expansion in powers of (RS/b)D-3 (b = impact parameter of the string center of mass). The deflection angle and cross sections are found. The quantum string corrections to the gravitational analogue of Rutherford's scattering are computed (these are of order α'2). The pair-creation or radiation amplitude we find here is of order α', it is non-thermal and of different origin than Hawking radiation. (orig.)