SCATTERING OF SUPERSTRINGS BY COSMIC STRINGS

We exactly solve the superstring scattering by a straight cosmic string. That is, we exactly quantize the Neveu-Schwarz-Ramond and the Green-Schwarz superstrings propagating in a conical space of deficit angle 8-pi-G-mu, mu being the cosmic-string tension. As for the purely bosonic string, if the superstring touches the cosmic string, the scattering is inelastic, since the internal superstring modes become excited and mixing of particle- and antiparticle-modes takes place, leading to different initial and final particle states. If there is no collision, the superstring only suffers a deflection of +/- 4-pi-G-mu and the oscillator modes only suffer a polarization change. All the transformations between the ingoing and outgoing states are explicitly computed in closed form. The mass formula and number operators are analyzed. We also generalize all these results to the case when the cosmic string is spinning; the new features, in this case, appear for the time string-coordinate; the propagation of fermionic coordinates is not affected by the cosmic-string spin.